Carbonyl functional inversion agents for water-in-oil latices and methods of use

ABSTRACT

Water-in-oil latices of water soluble or dispersible polymers and methods of using the same are presented. The latices include carbonyl functional inversion agents that provide rapid and complete inversion of the latices under conditions wherein the water source used to invert the latex is provided at high temperature, or includes a high level of total dissolved solids, or is both high temperature and high total dissolved solids.

TECHNICAL FIELD

The invention relates to water-in-oil latices of water dispersible polymers and compositions that provide for rapid inversion of the latices when diluted.

BACKGROUND

Crude oil development and production can include up to three distinct phases: primary, secondary, and tertiary (or enhanced) recovery. During primary recovery, the natural pressure of the reservoir or gravity drives oil into the wellbore, combined with artificial lift techniques (such as pumps) which bring the oil to the surface. But only about 10 percent of a reservoir's original oil in place is typically produced during primary recovery. Secondary recovery techniques extend a field's productive life generally by injecting water or gas to displace oil and drive it to a production wellbore, resulting in the recovery of 20 to 40 percent of the original oil in place.

Enhanced oil recovery, or EOR, is a generic term encompassing techniques for increasing the amount of crude oil that can be extracted from a subterranean formation such as an oil field. EOR techniques offer prospects for ultimately producing 30 to 60 percent, or more, of the reservoir's original oil in place. Three major categories of EOR have been found to be commercially successful to varying degrees:

Thermal recovery is the introduction of heat such as the injection of steam to lower the viscosity of the oil and improve its ability to flow through the reservoir.

Gas injection is the injection of gases such as natural gas, nitrogen, or carbon dioxide that expand in a reservoir to push additional oil to a production wellbore, or gases that dissolve in the oil to lower its viscosity and improve flow rate.

Chemical injection is the injection of polymer dispersions to increase the effectiveness of waterfloods, or the use of detergent-like surfactants to help lower the surface tension that often prevents oil droplets from moving through a reservoir. Chemical injection of a polymer is also referred to as polymer flooding. This method improves the vertical and areal sweep efficiency as a consequence of improving the water/oil mobility ratio. In addition, the polymer reduces the contrasts in permeability by preferentially plugging the high permeability zones flooded. This forces the water to flood the lower permeability zones and increases the sweep efficiency. The art in this area is well-developed for conventional oil recovery applications.

Of these techniques, polymer flooding using water-in-oil (w/o) latex products is particularly favored for use in offshore reservoirs and other relatively isolated operations due to the ease of use and relatively simple equipment requirements. Polymer flooding is generally accomplished by dissolving the selected polymer in water and injecting the polymer solution into the reservoir. However, since the target concentration of polymer in the polymer dispersions is typically about 1 wt % or less, transport at the target concentration is not economically efficient. Transporting the dried polymers, while economically efficient for the supplier, is not favorable for field use due to limited space for dry polymer make-down equipment and difficulties in fully hydrating the polymers in the field. To address these issues, various formulations have been developed to allow economically feasible transportation and storage. Specialized methods have also been developed to convert the formulations to use concentrations of fully hydrated polymers in the field.

Organic polymers traditionally used in EOR include water soluble polymers such as polyacrylamide homopolymers and copolymers with acrylic acid or conjugate base thereof and/or one or more other water soluble monomers, and hydrophobically modified water soluble polymers, also called associative polymers or associative thickeners. Associative thickeners are typically copolymers of acrylamide, acrylic acid, or both with about 1 mole % or less of a hydrophobic monomer such as a C₈-C₁₆ linear or branched ester of acrylic acid. Any of these water soluble polymers are deliverable as a dry powder, as a gel-like concentrate in water, or in the water phase of a w/o latex. Of these formats, water-in-oil latices have the advantage of being deliverable in a liquid format that is easily handled in the field because the latex viscosity is lower than that of a water solution of comparable wt % polymer. The liquid products are also easy to make down with little equipment and a small space footprint compared to that of dry polymer products.

Commercial w/o latices are formulated for EOR by dissolving monomer(s) in a high-solids aqueous solution to form a water phase (or monomer phase), mixing one or more hydrocarbon solvents and a surfactant or a blend thereof having a hydrophilic-lipophilic balance (HLB) of about 2 to 10 to form an oil phase, mixing the two phases using techniques to result in a water-in-oil emulsion or latex, and polymerizing the monomer via a standard free-radical initiation. The w/o latex may be a macroemulsion, nanoemulsion, microemulsion, or combination thereof. The free radical initiation may be radiation, photo, thermal, or redox initiation, or any combination thereof. After polymerization is complete, a higher HLB surfactant (HLB>10) or a blend thereof having an HLB>10 is often added to facilitate latex inversion when water is added. “Inversion” is a term of art to describe the dilution of w/o latices with a water source, causing destabilization of the latex and subsequent dissolution of the concentrated polymer particles. In some cases, the higher HLB surfactant is added in the field, immediately prior to addition of water to dilute the latex; or is added in-line with the water source used to dilute the latex. In other cases, the higher HLB surfactant is added directly to the w/o latex after polymerization is complete, and the latex is stable or even shelf stable. In such cases, careful control of type and amount of surfactant is required to provide a sufficiently stable latex to facilitate storage and transportation, while providing for improved inversion performance in the field.

Recently, there has arisen the need to address polymer flooding in challenging conditions encountered in reservoirs wherein the ambient or produced water contacted by the polymer includes high total dissolved solids, such as a high saline or hardness content, in some cases involving total dissolved solids of up to about 30 wt %. In some cases the ambient or produced water is tap water, hard water, brackish water, municipal waste water, produced water, or seawater. Field operators strongly prefer to use such water sources to dilute polymer flooding formulations to final use concentrations rather than employ purified water sources. Reasons for the preference include reducing costs by diverting some or all of the water source already being injected into a reservoir to dilute the polymer flooding formulations and reducing the environmental impact associated with employing a purified water source. However, use of such water sources leads to difficulties in dispersing the high molecular weight polymers to use concentrations. Inversion of w/o latices in such water sources can result in slow inversion times and/or the requirement of multistage dilution and mixing procedures; it can also result in coagulation, precipitation, or gross phase separation of polymer upon or after contact of the latex with the diluted water environment. Thus there is a need to address inversion of w/o latices in field conditions where the use water source has high total dissolved solids.

Another need in the industry is to address reservoirs where the water source contacted by a w/o latex is at an extreme temperature, such as 30° C. to 100° C. or −10° C. to 10° C. Extreme temperature water sources lead to difficulties in dispersing high molecular weight, water soluble polymers delivered in w/o latices, similarly to the difficulties encountered in the use of high total dissolved solids water sources. In some cases, conditions of both extreme temperature and high total dissolved solids are encountered in the ambient or produced water source employed to dilute polymer flooding formulations to use concentrations. Such conditions cause instability of w/o latices during inversion, evidenced by formation of gel particles, coagulum, polymer coated out on contact surfaces, and gross coalescence of phases (conventionally referred to as “separation”) and the like. The products of this instability cause plugged equipment in the field, reduced reservoir permeability, plugged formation, and ultimately failure to accomplish mobility control within the reservoir. These problems remain largely unaddressed by conventional formulations, methods, and equipment developed for inversion of w/o latices in the field. For example, formulations described in US Patent Application Publication No. 2014/0051620 A1, which comprise an inversion agent such as glycerol, do not provide satisfactory performance under conditions using water sources having high total dissolved solids, extreme temperature, or both.

As a result, there is a substantial need in the industry to develop technologies suitable for carrying out enhanced oil recovery in reservoirs where high temperature water sources, high total dissolved solids water sources, or both are used in conjunction with EOR. There is a substantial need in the industry for w/o polymer latices that invert rapidly to form stable, fully hydrated or dissolved polymer solutions at water temperatures of 30° C. to 100° C. There is a substantial need in the industry for w/o polymer latices that invert rapidly to form stable, fully hydrated or dissolved polymer solutions using water sources having up to 30 wt % total dissolved solids. There is a substantial need in the industry for w/o polymer latices that invert rapidly to form stable, fully hydrated or dissolved polymer solutions at polymer concentrations of 1 wt % or less using water sources having high total dissolved solids, high temperature, or both.

SUMMARY

Described herein are water-in-oil (w/o) latices. The latices are formed by combining about 0.1 wt % to 20.0 wt % of a carbonyl functional inversion agent with about 15 wt % to 70 wt % of a water soluble or dispersible polymer comprising 1 mol % to about 100 mol % acrylamide monomers; and about 0.1 wt % to 20.0 wt % of an inversion surfactant having a hydrophilic/lipophilic balance of 10 or greater. In some embodiments, the w/o latex comprises about 0.1 wt % to 5.0 wt % of a carbonyl functional inversion agent that is a hydrotrope; about 15 wt % to 70 wt % of the water soluble polymer; about 0.1 wt % to 20.0 wt % of the inversion surfactant; about 3 wt % to 50 wt % water; about 10 wt % to 40 wt % of a compound or blend thereof that is less than 0.1 wt % soluble in water at 25° C. and is substantially a liquid over the range of 20° C. to 90° C. and comprising linear, branched, or cyclic hydrocarbon moieties; and about 20 wt % or less of a latex surfactant characterized as having a hydrophilic/lipophilic balance of between 2 and 10.

Also described herein is a method of forming an invertible latex, the method comprising a) forming a water-in-oil latex comprising about 15 wt % to 70 wt % of a water soluble or dispersible polymer; about 3 wt % to 50 wt % water; about 10 wt % to 40 wt % of a compound or blend thereof that is less than 0.1 wt % soluble in water at 25° C. and is substantially a liquid over the range of 20° C. to 90° C. and comprising linear, branched, or cyclic hydrocarbon moieties; and about 20 wt % or less of a latex surfactant characterized as having a hydrophilic/lipophilic balance of between 2 and 10; and b) adding to the latex about 0.1 wt % to 20.0 wt % of an inversion surfactant characterized as having a hydrophilic/lipophilic balance of 10 or greater and about 0.1 wt % to 5.0 wt % of a carbonyl functional inversion agent to form an invertible latex.

Also described herein is a method of recovering hydrocarbon compounds from a subterranean reservoir, the method comprising a) forming an invertible latex comprising about 15 wt % to 70 wt % of a water soluble or dispersible polymer, about 3 wt % to 50 wt % water, about 10 wt % to 40 wt % of a compound or blend thereof that is less than 0.1 wt % soluble in water at 25° C. and is substantially a liquid over the range of 20° C. to 90° C. and comprising linear, branched, or cyclic hydrocarbon moieties, and about 20 wt % or less of a latex surfactant characterized as having a hydrophilic/lipophilic balance of between 2 and 10; and adding to the latex about 0.1 wt % to 20.0 wt % of an inversion surfactant characterized as having a hydrophilic/lipophilic balance of 10 or greater and about 0.1 wt % to 5.0 wt % of a carbonyl functional inversion agent; b) adding a water source to the invertible latex in a single addition to form a polymer flooding solution comprising about 100 ppm to 10,000 ppm of the water soluble or dispersible polymer; c) injecting the polymer flooding solution into the subterranean reservoir; and d) recovering the hydrocarbon compounds.

Additional advantages and novel features of the invention will be set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned through routine experimentation upon practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a line graph of torque monitor data at 60° C. showing the invertibility of w/o latices comprising 3 wt % of a carbonyl functional inversion agent and 3.3% of TDA-12 as an inverting surfactant ([polymer]=10000 ppm in 3.5% SSW).

FIG. 2 is a line graph of torque monitor data at 60° C. showing the invertibility of w/o latices comprising 3 wt % of a carbonyl functional inversion agent and 3.3% of TDA-12 as an inverting surfactant ([polymer]=10000 ppm in 3.5% SSW).

FIG. 3 is a line graph of torque monitor data at 60° C. showing the invertibility of w/o latices comprising 3 wt % of an carbonyl functional inversion agent and 3.3% of TDA-12 as an inverting surfactant ([polymer]=10000 ppm in 3.5% SSW).

FIG. 4 is a line graph of torque monitor data at 60° C. showing the invertibility of w/o latices comprising 2 wt % of a carbonyl functional inversion agent and 3.3% of TDA-12 as an inverting surfactant ([polymer]=10000 ppm in 3.5% SSW).

FIG. 5 is a line graph of torque monitor data at room temperature showing the invertibility of w/o latices comprising 3 wt % of a carbonyl functional inversion agent and 3.3% of TDA-12 as an inverting surfactant ([polymer]=10000 ppm in 3.5% SSW).

FIG. 6 is a line graph of torque monitor data at 4° C. showing the invertibility of w/o latices comprising 3 wt % of a carbonyl functional inversion agent and 3.3% of TDA-12 as an inverting surfactant ([polymer]=10000 ppm in 3.5% SSW).

DETAILED DESCRIPTION

Although the present disclosure provides references to preferred embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. Various embodiments will be described in detail with reference to the drawings. Reference to various embodiments does not limit the scope of the claims attached hereto. Additionally, any examples set forth in this specification are not intended to be limiting and merely set forth some of the many possible embodiments for the appended claims.

DEFINITIONS

As used herein, the term “polymer” means a water soluble or water dispersible polymer. The term “polymer” encompasses and includes homopolymers, copolymers, terpolymers and polymers with more than 3 monomers, crosslinked or partially crosslinked polymers, and combinations or blends of these.

The term “monomer” is used in context to mean an ethylenically unsaturated polymerizable compound or the polymerized residue thereof. As used herein, the term “anionic monomer” means an unsaturated compound or polymerized residue thereof bearing an acidic group, or a salt thereof. As used herein, the term “cationic monomer” means an unsaturated compound or polymerized residue thereof bearing a positive charge, or a salt thereof.

As used herein, the term “polymer solution” or “polymer dispersion” means a polymer composition substantially dispersed or dissolved in water, a water source, or a water-based solution. The polymer solution is a solution as formed, or in the case of some EOR applications the solution before injection, during injection, or after injection as determined by context. Water-based solutions include one or more dissolved salts, buffers, acids, bases, surfactants, or other dissolved, dispersed, or emulsified compounds, materials, components, or combinations thereof.

As used herein, the term “water source” means a source of water comprising, consisting essentially of, or consisting of fresh water, deionized water, distilled water, produced water, municipal water, waste water such as runoff water or municipal waste water, treated or partially treated waste water, well water, brackish water, “gray water”, sea water, or a combination of two or more such water sources as determined by context. In some embodiments, a water source includes one or more salts, ions, buffers, acids, bases, surfactants, or other dissolved, dispersed, or emulsified compounds, materials, components, or combinations thereof. In some embodiments, a water source includes about 0 wt % to 30 wt % total dissolved solids. Generally and as determined by context, the term “water source” includes high total dissolved solids water sources, high temperature water sources, and water sources that are both high total dissolved solids and high temperature water sources.

As used herein, the term “high temperature” means about 30° C. to 100° C., as specified or determined by context.

As used herein, the term “high total dissolved solids” refers to a water source having at least 1 wt % non-polymeric solids dissolved therein, and in embodiments up to about 30 wt % non-polymeric solids dissolved therein. In general, “saline” or “salinity” refers to a water source wherein a portion, in some embodiments a substantial portion, of the total dissolved solids are salts, as determined by context.

As used herein, the terms “water-in-oil latex” or “w/o latex” mean a discontinuous internal water phase within a continuous oil phase, wherein the water phase includes at least one monomer or polymer. In general and as determined by context, these terms denote a latex prior to addition of inverting surfactants.

As used herein, the term “oil” or “hydrocarbon solvent” as applied to an oil phase of a water-in-oil latex, means any compound or blend thereof that is less than 0.1 wt % soluble in water at 25° C., is substantially chemically inert within a w/o latex as described herein, and is a liquid over at least the range of 20° C. to 100° C.

As used herein, the term “water phase” means a water source having at least a monomer or polymer dispersed or dissolved therein, further wherein the dispersion or solution is a discontinuous phase within a w/o latex.

As used herein, the term “stable” as applied to a latex or emulsion means a kinetically stable latex or emulsion that absent any force applied, temperature change, or chemical added to a latex, the latex is or is capable of being substantially free of coagulation, plating out, precipitation, gross coalescence of phases (conventionally referred to as “separation”) or any other evidence of instability conventionally associated with water-in-oil latices for at least about 24 hours at about 20° C. As used herein, the term “shelf stable” means stable for at least 2 months. As used herein, the term “freeze-thaw stable” means stable after at least 1 freeze-thaw cycle.

As used herein, the term “invertible latex” means a w/o latex additionally including at least one inversion surfactant and at least one inversion agent, the inversion agent comprising at least one carbonyl functional compound.

As used herein, the term “invert” or “inversion” as applied to the w/o latices of the invention means to contact an invertible latex with a water source in an amount sufficient to form a polymer flooding solution.

As used herein, the term “polymer flooding solution” or “polymer solution” means a polymer solution or dispersion of about 100 ppm (0.01 wt %) to 10,000 ppm (1.00 wt %) resulting from the inversion of an invertible latex.

As used herein, the term “single component” as applied to the w/o latices of the invention means that at least one inversion surfactant and at least one inversion agent are added to an existing w/o latex and the combination is shelf stable. The term is used in contrast to inversion surfactants or other compounds added in-line during injection and inversion.

As used herein, the term “optional” or “optionally” means that the subsequently described component, event or circumstance may be, but need not be present or occur. The description therefore discloses and includes instances in which the event or circumstance occurs and instances in which it does not, or instances in which the described component is present and instances in which it is not.

As used herein, the term “about” modifying, for example, the quantity of an ingredient in a composition, concentration, volume, temperature, time, yield, flow rate, pressure, and like values, and ranges thereof, employed in describing the embodiments of the disclosure, refers to variation in the numerical quantity that can occur, for example, through typical measuring and handling procedures used for making compounds, compositions, concentrates or use formulations; through inadvertent error in these procedures; through differences in the manufacture, source, or purity of starting materials or ingredients used to carry out the methods, through standard operating machine error, and like proximate considerations. The term “about” also encompasses amounts that differ due to aging of a formulation with a particular initial concentration or mixture, and amounts that differ due to mixing or processing a formulation with a particular initial concentration or mixture. Where modified by the term “about” the claims appended hereto include equivalents according to this definition.

As used herein, the term “substantially” means “consisting essentially of”, as that term is construed in U.S. patent law, and includes “consisting of” as that term is construed in U.S. patent law. For example, a solution that is “substantially free” of a specified compound or material may be free of that compound or material, or may have a minor amount of that compound or material present, such as through unintended contamination or incomplete purification. A “minor amount” may be a trace, an unmeasurable amount, an amount that does not interfere with a value or property, or some other amount as provided in context. A composition that has “substantially only” a provided list of components may consist of only those components, or have a trace amount of some other component present, or have one or more additional components that do not materially affect the properties of the composition. Additionally, “substantially” modifying, for example, the type or quantity of an ingredient in a composition, a property, a measurable quantity, a method, a value, or a range, employed in describing the embodiments of the disclosure, refers to a variation that does not affect the overall recited composition, property, quantity, method, value, or range thereof in a manner that negates an intended composition, property, quantity, method, value, or range. Where modified by the term “substantially” the claims appended hereto include equivalents according to this definition.

Water-in-Oil Latices

We have found inversion agents that provide rapid and complete inversion of water-in-oil (w/o) latices of water soluble polymers under conditions wherein the water source used to invert the latex is provided at high temperature, or includes a high level of total dissolved solids, or is both high temperature and high total dissolved solids. The w/o latices useful in conjunction with the compositions and methods of the invention are conventional latices employed in one or more EOR applications, wherein the inversion agents are added to the w/o latices to facilitate inversion to yield a polymer solution for EOR. Polymer solutions for EOR conventionally target a concentration of about 1.00 wt % or less. The compositions and methods of the invention are easily carried out using conventional materials and equipment familiar to one of skill in w/o latex formation for EOR.

Polymers useful in the w/o latices include conventional EOR polymers as well as variations, mixtures, or derivatives thereof. The invention is not particularly limited as to the polymer employed in the water phase of the w/o latices, however, in embodiments the polymer is water soluble or fully dispersible to result in increased viscosity suitable for one or more EOR applications at concentrations of 1 wt % or less. Thus, polyacrylamides, polyacrylates, copolymers thereof, and hydrophobically modified derivatives of these (associative thickeners) are the most commonly employed EOR polymers; all are usefully employed in the w/o latices. Associative thickeners typically include about 1 wt % or less, based on total weight of dry polymer, of a monomer having a long-chain hydrocarbon functionality intended to produce physical or associative crosslinking in a water-based polymer dispersion. Such hydrophobically associating moieties are well known in the industry. In some embodiments, the hydrocarbyl functionality includes 8 to 20 carbons, or 10 to 20 carbons, or 12 to 20 carbons arranged in a linear, branched, or cyclic conformation. In some embodiments, the hydrophobically associating monomers are present in the polymer compositions at about 1 wt % or less of the total weight of the polymer composition, for example about 0.01 wt % to 1.00 wt %, or about 0.1 wt % to 1.00 wt %, or about 0.20 wt % to 1.00 wt % of the total weight of the polymer composition.

Other monomers usefully incorporated into the polymers and copolymers with acrylamide, acrylic acid, or both include cationic monomers, anionic monomers, and nonionic monomers. Nonlimiting examples of cationic monomers include N,N-diallyl-N,N-dimethylammonium chloride (DADMAC), N-alkyl ammonium salts of 2-methyl-1-vinyl imidazole, N-alkyl ammonium salts of 2-vinyl pyridine or 4-vinyl pyridine, N-vinyl pyridine, and trialkylammonium alkyl esters and amides derived from acrylic acid or acrylamide, respectively. Nonlimiting examples of anionic monomers include methacrylic acid, 2-acrylamido-2-methylpropane sulfonic acid (AMS), vinylphosphonic acid, and vinyl sulfonic acid and conjugate bases or neutralized forms thereof (salts). Nonlimiting examples of nonionic monomers include methacrylamide and alkyl ester or amide derivatives of acrylic acid or acrylamide, such as N-methyl acrylamide or butyl acrylate.

Polymers employed for EOR are desirably high molecular weight, as conventionally employed in EOR applications. Higher molecular weight increases the efficacy of the polymers in viscosifying water. However, higher molecular weight also increases difficulty in dissolution due to the high level of chain entanglement between polymer strands as well as strong hydrogen bonding between polymer functionalities such as amides and carboxylates. In embodiments, the polymers usefully incorporated in the w/o latices have a weight average molecular weight (M_(w)) of about 5×10⁵ to 1×10⁸ g/mol, or about 1×10⁶ to 5×10⁷ g/mol, or about 5×10⁶ to 2×10⁷ g/mol.

In embodiments, any polymer(s) useful in the w/o latices disclosed herein includes a cross-linking monomer or polymer. The crosslinker may be labile, non-labile, or a combination thereof. The labile crosslinker may be a glyoxal cross-linking monomer as described in U.S. Patent Application Publication No. 2014/0209304, which is incorporated by reference herein in its entirety. The non-labile crosslinker may be methylene bis(acrylamide) as described in U.S. Pat. No. 7,300,973, which is incorporated by reference herein in its entirety. In embodiments, the polymer comprises about 1 mol % to about 100 mol % acrylamide monomers, or about 1 mol % to about 90 mol %, or about 1 mol % to about 80 mol %, or about 1 mol % to about 70 mol %, or about 1 mol % to about 60 mol %, or about 1 mol % to about 50 mol %, or about 1 mol % to about 40 mol %, or about 1 mol % to about 30 mol %, or about 1 mol % to about 20 mol %, or about 1 mol % to about 10 mol %, or about 10 mol % to about 100 mol %, or about 20 mol % to about 100 mol %, or about 30 mol % to about 100 mol %, or about 40 mol % to about 100 mol %, or about 50 mol % to about 100 mol %, or about 60 mol % to about 100 mol %, or about 70 mol % to about 100 mol %, or about 80 mol % to about 100 mol %, or about 90 mol % to about 100 mol %, or about 20 mol % to about 80 mol %, or about 30 mol % to about 70 mol %, or about 40 mol % to about 60 mol %, or about 60 mol % to about 80 mol % acrylamide monomers.

In embodiments, the polymer comprises about 0.1 ppm to about 20000 ppm labile or non-labile cross-linked monomer units based on the weight of the polymer, or about 0.1 ppm to about 10000 ppm, or about 0.1 ppm to about 5000 ppm, or about 0.1 ppm to about 1000 ppm, or about 0.1 ppm to about 100 ppm, or about 1 ppm to about 20000 ppm, or about 10 ppm to about 20000 ppm, or about 100 ppm to about 20000 ppm, or about 1000 ppm to about 20000 ppm, or about 5000 ppm to about 20000 ppm, or about 10000 ppm to about 20000 ppm, or about 100 ppm to about 10000 ppm, or about 1000 ppm to about 5000 ppm cross-linked monomer units based on the weight of the polymer. In embodiments, the cross-linking monomer is glyoxal bis(acrylamide).

In embodiments, the polymer including the cross-linking monomer comprises about 100 ppm to about 10000 ppm of a w/o latex, or about 100 ppm to about 5000 ppm, or about 100 ppm to about 1000 ppm, or about 100 ppm to about 500 ppm, or about 500 ppm to about 10000 ppm, or about 1000 ppm to about 10000 ppm, or about 5000 ppm to about 10000 ppm, or about 500 ppm to about 5000 ppm, or about 100 ppm to about 1000 ppm, of a w/o latex.

In embodiments, one or more polymers are present substantially within the water phase in an w/o latex. In embodiments, the polymers are present within the w/o latices at about 15 wt % to 70 wt % based on the total weight of the latex, or about 17 wt % to 70 wt %, or about 19 wt % to 70 wt %, or about 21 wt % to 70 wt %, or about 23 wt % to 70 wt %, or about 25 wt % to 70 wt %, or about 15 wt % to 68 wt %, or about 15 wt % to 66 wt %, or about 15 wt % to 64 wt %, or about 15 wt % to 62 wt %, or about 15 wt % to 60 wt %, or about 15 wt % to 58 wt %, or about 15 wt % to 56 wt %, or about 25 wt % to 65 wt %, or about 30 wt % to 60 wt %, or about 30 wt % to 60 wt % based on the total weight of the latex.

The polymers present within the water phase of a w/o latex are often, though not exclusively, formed in situ by dissolving one or more monomers in the water phase, then adding a water phase into an oil phase bearing a surfactant to form the emulsion, followed by polymerization of the monomers to form a polymer w/o latex. Such latices are used for EOR applications.

Also present in the w/o latex is an amount of water sufficient to form a water phase within the latex. Water is present in the w/o latex at about 3 wt % to 50 wt % based on the total weight of the latex, or about 5 wt % to 50 wt %, or about 10 wt % to 50 wt %, or about 15 wt % to 50 wt %, or about 20 wt % to 50 wt %, or about 25 wt % to 50 wt %, or about 3 wt % to 45 wt %, or about 3 wt % to 40 wt %, or about 3 wt % to 35 wt %, or about 3 wt % to 30 wt %, or about 3 wt % to 25 wt %, or about 5 wt % to 45 wt %, or about 5 wt % to 40 wt %, or about 5 wt % to 35 wt %, or about 5 wt % to 30 wt %, or about 5 wt % to 25 wt % based on the total weight of the w/o latex. In some embodiments, the water is a water source.

Also present in the w/o latex is an amount of oil sufficient to form an oil phase within the latex. In some embodiments, the oil is not flammable at temperatures less than about 90° C., or less than about 80° C., or less than about 70° C. In some embodiments, the oil is a mixture of compounds, wherein the mixture is less than 0.1 wt % soluble in water at 25° C. and is substantially a liquid over the range of 20° C. to 90° C. In some embodiments, the oil comprises, consists essentially of, or consists of one or more linear, branched, or cyclic hydrocarbon moieties, aryl or alkaryl moieties, or combinations of two or more such moieties. In some embodiments, the oil has a density of about 0.8 g/L to 1.0 g/L, for example about 0.8 g/L to 0.9 g/L. Examples of suitable oils include decane, dodecane, isotridecane, cyclohexane, toluene, xylene, and mixed paraffin solvents such as those sold under the trade name ISOPAR® by ExxonMobil Corp. of Irving, Tex. In embodiments, the oil is present in the w/o latex at about 10 wt % to 40 wt % based on the total weight of the w/o latex, or about 15 wt % to 40 wt %, or about 20 wt % to 40 wt %, or about 22 wt % to 40 wt %, or about 24 wt % to 40 wt %, or about 26 wt % to 40 wt %, or about 28 wt % to 40 wt %, or about 30 wt % to 40 wt %, or about 10 wt % to 38 wt %, or about 10 wt % to 36 wt %, or about 10 wt % to 34 wt %, or about 10 wt % to 32 wt %, or about 10 wt % to 30 wt %, or about 10 wt % to 25 wt %, or about 10 wt % to 20 wt %, or about 15 wt % to 35 wt %, or about 20 wt % to 30 wt % based on the total weight of the w/o latex.

Also present in the w/o latex is one or more latex surfactants. Latex surfactants are employed to form and stabilize the w/o latices during polymerization and to maintain latex stability until inversion. Generally the latex surfactant is present at about 20 wt % or less based on the weight of the latex. Conventionally employed surfactants for w/o latices used for EOR applications include nonionic ethoxylated fatty acid esters, ethoxylated sorbitan fatty acid esters, sorbitan esters of fatty acids such as sorbitan monolaurate, sorbitan mono stearate, and sorbitan monooleate, block copolymers of ethylene oxide and hydroxyacids having a C₁₀-C₃₀ linear or branched hydrocarbon chain, and blends of two or more of these targeted to achieve a selected hydrophilic/lipophilic balance (HLB). Those of skill will understand that a plethora of surfactants are employed throughout the industry to form and stabilize w/o latices, serving as emulsifiers for polymerization of monomers and further maintaining emulsion stability of the polymer formed therein until subsequent use in the field. Any nonionic surfactants and blends thereof conventionally employed in w/o latices for EOR applications are suitably employed in conjunction with the present invention. In embodiments, the latex surfactant is a single nonionic surfactant or blend thereof having a combined HLB value of about 2 to 10, for example about 3 to 10, or about 4 to 10, or about 5 to 10, or about 6 to 10, or about 7 to 10, or about 8 to 10, or about 2 to 9, or about 2 to 8, or about 2 to 7, or about 2 to 6, or about 2 to 5, or about 3 to 9, or about 4 to 8.

Representative amounts of the above listed materials are suitably included in one or more w/o latices useful to stabilize one or more EOR applications, wherein the amounts are suitably selected to provide optimal kinetic stability of the emulsion. In some embodiments, amounts of the above listed materials are suitably employed in one or more w/o latices to form a microemulsion or a nanoemulsion, wherein such emulsions are characterized by one or more properties of thermodynamic stability and optical transparency. Representative amounts of these materials are shown below, wherein these amounts are intended to be representative of the w/o latices useful in conjunction with the methods and materials of the invention. Useful w/o latices are not limited to those shown below. A specific example of a w/o latex formulation is provided in Example 3. Where amounts listed below do not add up to 100 wt %, one or more additional components are also present in the latex.

Amount in a w/o Latex, wt % Phase Material Latex 1 Latex 2 Latex 3 Latex 4 Latex 5 Oil Oil 25 30 10 20 25 (solvent) Latex 15 5 3 5 20 Surfactant Water Monomer 50 25 50 35 40 or Polymer Water 5 40 10 3 10

The w/o latices optionally include one or more additives. Salts, buffers, acids, bases, dyes, thermal stabilizers, metal chelators, coalescing solvents, and the like are optionally included in the w/o latices. In some embodiments, the additives include one or more corrosion inhibitors, scale inhibitors, emulsifiers, water clarifiers, hydrogen sulfide scavengers, gas hydrate inhibitors, biocides, pH modifiers, antioxidants, asphaltene inhibitors, or paraffin inhibitors. While the amount of an additive usefully employed in the w/o latex depends on the additive and the intended application, in general the amount of any individual additive is about 0 wt % to 5 wt % based on the total weight of the w/o latex, or about 0 wt % to 4 wt %, or about 0 wt % to 3 wt %, or about 0 wt % to 2 wt %, or about 0 wt % to 1 wt % based on the total weight of the latex.

In embodiments, the w/o latices are made using conventional equipment and methodology. Thus, in embodiments a w/o latex containing the monomers is formed and the polymerization is conducted within the water phase of the latex. In other embodiments the polymer is formed in a water solution, and the solution is used to form a w/o latex. In such embodiments, the w/o latex is formed after polymerization is complete by adding one or more surfactants and one or more oils to the water-based polymer composition and emulsifying the combined components as described above.

In embodiments, the water in the w/o latex is substantially removed after polymerization to produce a more concentrated latex product by distillation, vacuum drying, spray drying, or a combination thereof. In embodiments, the oil in the w/o latex is substantially removed and recycled after polymerization to produce a more concentrated latex product by distillation, vacuum drying, spray drying, or any combination thereof.

Inversion Surfactants

Inversion of the presently disclosed w/o latices is facilitated by an inversion surfactant. Useful inversion surfactants comprise, consist essentially of, or consist of surfactants or blends thereof having an HLB of about 10 to 40, or about 10 to 35, or about 10 to 30, or about 10 to 25, or about 10 to 20, or about 10 to 15, or about 15 to 40, or about 20 to 40, or about 25 to 40, or about 30 to 40, or about 35 to 40, or about 15 to 35, or about 20 to 30. In some embodiments, the inversion surfactant is nonionic and includes one or more compounds comprising one or more ethoxy groups, propoxy groups, or a combination thereof. In some embodiments, the inversion surfactant is ionic and includes one or more carboxylate, sulfonate, phosphate, phosphonate, phosphonium, or ammonium moieties. In some embodiments, the inversion surfactant includes a linear or branched C₈-C₂₀ hydrocarbyl moiety. In some such embodiments, the inversion surfactant is an alkoxylated alcohol such as an ethoxylated, propoxylated, or ethoxylated/propoxylated alcohol, wherein the alcohol includes a linear or branched C₈-C₂₀ hydrocarbyl moiety. In some such embodiments, the inversion surfactant includes about 4 and 40 ethylene oxide repeat units and 0 to about 10 propylene oxide repeat units. In some embodiments, the inversion surfactant includes a sorbitan moiety. In some embodiments, the inversion surfactant is a block copolymer. In some such embodiments, the block copolymer is linear, branched, or hyperbranched. Examples of suitable inversion surfactants are listed in McCutcheon's Emulsifiers & Detergents, MC Publishing Co., 2015 edition.

The inversion surfactant may be added before, concurrently with, or after addition of an inversion agent, described below, to a w/o latex. In embodiments, in order to facilitate inversion of a w/o latex, the inversion surfactant is added to a latex at about 0.1 wt % to 20 wt % based on the total weight of the w/o latex, or about 0.1 wt % to 15 wt %, 0.1 wt % to 10 wt %, or about 0.1 wt % to 7.5 wt %, 0.1 wt % to 6.0 wt % based on the total weight of the w/o latex, or about 0.5 wt % to 5.5 wt %, or about 1.0 wt % to 5.0 wt %, or about 1.5 wt % to 4.5 wt %, or about 2.0 wt % to 4.0 wt %, or about 2.5 wt % to 3.5 wt %, or about 0.1 wt % to 5.5 wt %, or about 0.1 wt % to 5.0 wt %, or about 0.1 wt % to 4.5 wt %, or about 0.1 wt % to 4.0 wt %, or about 0.1 wt % to 3.5 wt %, or about 0.5 wt % to 6.0 wt %, or about 1.0 wt % to 6.0 wt %, or about 1.5 wt % to 6.0 wt %, or about 2.0 wt % to 6.0 wt %, or about 2.5 wt % to 6.0 wt %, or about 3.0 wt % to 6.0 wt %, based on the total weight of the w/o latex.

The amount of inversion surfactant may be reduced when an inversion agent (described below) is added to a w/o latex. In embodiments, an inversion agent is added to a w/o latex and the amount of inversion surfactant is reduced by up to 50% compared to a w/o latex that does not include an inversion agent. In embodiments, the inversion agent is added to a latex at about 0.1 wt % to 10 wt % based on the total weight of the w/o latex, or about 0.1 wt % to 7.5 wt %, 0.1 wt % to 5.0 wt % based on the total weight of the w/o latex, or about 1.5 wt % to 4.5 wt %, or about 2.0 wt % to 4.0 wt %, or about 2.5 wt % to 3.5 wt %, or about 0.1 wt % to 4.5 wt %, or about 0.1 wt % to 4.0 wt %, or about 0.1 wt % to 3.5 wt %, or about 0.5 wt % to 5.0 wt %, or about 1.0 wt % to 5.0 wt %, or about 1.5 wt % to 5.0 wt %, or about 2.0 wt % to 5.0 wt %, or about 2.5 wt % to 5.0 wt %, or about 3.0 wt % to 5.0 wt %, based on the total weight of the w/o latex.

Inversion Agents

We have found inversion agents that when added to conventional w/o latices of water soluble polymers in the presence of an inverting surfactant form invertible latices. The invertible latices are characterized by the rapid and complete inversion thereof under conditions wherein the water source used to invert the latex is about 30° C. to 100° C., or about 40° C. to 100° C., or about 50° C. to 100° C., or about 60° C. to 100° C. Further, the invertible latices are characterized by the rapid and complete inversion thereof under conditions wherein the water source used to invert the latex includes about 0.1 to 30 wt % total dissolved solids. Still further, the invertible latices are characterized by the rapid and complete inversion thereof under conditions wherein the water source used to invert the latex is about 30° C. to 100° C. and further includes about 0.1 to 30 wt % total dissolved solids.

In embodiments, inversion agents of the invention comprise, consist essentially of, or consist of a carbonyl functional compound. As used herein, a carbonyl functional compound is a compound having at least one carboxyl, carboxamide, or hydroxamate group. In some embodiments, the carbonyl compound is a mixture of two or more carbonyl functional compounds.

In embodiments, the carbonyl functional compounds are not surface active agents in w/o latices. That is, they do not tend to lower the surface tension between water and oil phases in a w/o latex. As used herein, a compound that is not a surfactant is one that reduces the surface tension of water in a 0.5% active solution at room temperature by 20% or less, or by 10% or less, or by 5% or less. (Example 9.)

In embodiments, inversion agents of the invention comprise, consist essentially of, or consist of a hydrotrope. As used herein, a hydrotrope is a water soluble compound that solubilizes hydrophobic compounds in an aqueous solution and that includes at least one hydrophilic and at least one minor hydrophobic moiety. As used herein, a minor hydrophobic moiety is one that is insufficient to promote spontaneous self-aggregation or is insufficient to promote accumulation at interfaces or is not a long uninterrupted hydrophobic chain or is any combination of the foregoing. As used herein, a long uninterrupted hydrophobic chain is a hydrocarbyl moiety having 5 or more carbon atoms.

In embodiments, inversion agents of the invention comprise, consist essentially of, or consist of compounds with an HLB as calculated by the Davies formula:

HLB=Σ(Hydrophilic group contributions)−Σ(Hydrophobic group contributions)+7

of greater than about 19, or greater than about 20, or greater than about 25, or greater than about 30, or greater than about 35, or greater than about 40, or about 20 to 150, or about 20 to 140, or about 20 to 130, or about 20 to 120, or about 20 to 110, or about 20 to 100, or about 20 to 90, or about 20 to 80, or about 20 to 70, or about 20 to 60, or about 20 to 50, or about 25 to 150, or about 30 to 150, or about 35 to 150, or about 40 to 150, or about 45 to 150.

Examples of carbonyl functional inversion agents comprise, consist essentially of, or consist of hydroxycarboxylic acids or salts thereof, hydroxyamides, and amino acids. Examples of hydroxycarboxylic acids or salts thereof include carboxymethyl polyol ethers having at least 4 carbon atoms, such as carboxymethyl-1,2-diol, carboxymethyl glycerol, carboxymethyl erythritol, carboxymethyl sorbitol, and carboxymethyl polyglycerol; α-hydroxyacids such as glycolic acid, lactic acid, tartaric acid, and malic acid; and β-hydroxyacids such as hydroxypropionic acid, carnitine, and salicylic acid. Carboxymethyl polyols may be synthesized according to Examples 1 and 2. Examples of hydroxyamides include N-hydroxysuccinimide. Examples of amino acids include glycine, alanine, lysine, serine, and threonine.

Unexpectedly, the inversion agent, or the inversion agent in combination with the inversion surfactant, reduces the bulk viscosity of the invertible latex. In embodiments, reduced bulk viscosity provides better pumpability for pumping and transferring the invertible latex and/or the polymer flooding solution. The inversion agent, or the inversion agent in combination with the inversion surfactant, may increase the speed of the inversion process, increase the completeness of the inversion process, or both increase the speed and completeness. The resulting polymer flooding solution may thereby demonstrate improved performance.

In embodiments, the inversion agents, or the inversion agents in combination with an inversion surfactant, of the present disclosure facilitate inversion of an invertible latex compared to an invertible latex comprising no inversion agent and/or compared to an invertible latex comprising a known inversion agent such as glycerol. The inversion agents, or the inversion agents in combination with an inversion surfactant, of the present disclosure increase the speed and/or completeness of the inversion process compared to an invertible latex comprising no inversion agent and/or compared to an invertible latex comprising a known inversion agent such as glycerol.

In embodiments, the inversion agents, or the inversion agents in combination with an inversion surfactant, facilitate inversion of an invertible latex under conditions wherein the water source used to invert the latex is about 0° C. to 100° C. In some examples, the inversion agents, or the inversion agents in combination with an inversion surfactant, facilitate inversion of an invertible latex under conditions wherein the water source used to invert the latex is about 4° C., about 25° C., or about 60° C. (Examples 7 and 8.)

In embodiments, the inversion agents, or the inversion agents in combination with an inversion surfactant, facilitate inversion of an invertible latex under conditions wherein the water source used to invert the latex includes about 0.1 to 30 wt % total dissolved solids. In some examples, the inversion agents, or the inversion agents in combination with an inversion surfactant, facilitate inversion of an invertible latex under conditions wherein the water source used to invert the latex includes about 3.5% total dissolved solids. (Examples 7 and 8.)

In embodiments, the inversion agents, or the inversion agents in combination with an inversion surfactant, facilitate inversion of an invertible latex under conditions wherein the water source used to invert the latex is about 0° C. to 100° C. and includes about 0.1 to 30 wt % total dissolved solids. In some examples, the inversion agents, or the inversion agents in combination with an inversion surfactant, facilitate inversion of an invertible latex under conditions wherein the water source used to invert the latex is about 4° C., about 25° C., or about 60° C. and includes about 3.5% total dissolved solids. (Examples 7 and 8.)

Without being limited to any mechanism or mode of action, inversion agents may form hydrogen bonds and/or may affect the osmotic pressure of monomer- or polymer-comprising droplets of the discontinuous internal water phase within the continuous oil phase of a w/o latex. The inversion agents may increase the osmotic pressure of the droplets such that the droplets swell. When combined with a water source to form a polymer flooding solution, the swollen droplets may rupture more easily, facilitating the release of the monomer or polymer into the water. Separately from, or in addition to, the effect on osmotic pressure, the inversion agents may chelate ions within the droplets. Chelation may prevent or limit interaction of ions with the surfactant and thereby facilitate inversion. In embodiments, the branched structure of some inversion agents, such as carboxymethyl polyglycerols, may facilitate inversion compared to the inclusion of straight chain molecules.

In embodiments, the inversion agent is added to a latex in an amount sufficient to facilitate the inversion of a w/o latex. The amount is not so high that it causes the emulsion to break or otherwise be unstable. In embodiments, the inversion agent is added to a latex in an amount less than amounts of known inversion agents. For example, the presently disclosed inversion agent may be added in an amount of from about 0.1 wt % to 5.0 wt % based on the total weight of the w/o latex. In contrast, and as disclosed in US 2014/0051620, glycerol is preferably added in an amount of from about 5 to about 20% by weight.

In embodiments, in order to facilitate inversion of a w/o latex, the inversion agent is added to a latex at about 0.1 wt % to 20.0 wt % based on the total weight of the w/o latex, or about 0.1 wt % to 15.0 wt %, or about 0.1 wt % to 10.0 wt %, or about 0.1 wt % to 7.5 wt %, or about 0.1 wt % to 5.0 wt %, or about 0.5 wt % to 4.5 wt %, or about 1.0 wt % to 4.0 wt %, or about 1.5 wt % to 3.5 wt %, or about 2.0 wt % to 3.0 wt %, or about 0.1 wt % to 4.5 wt %, or about 0.1 wt % to 4.0 wt %, or about 0.1 wt % to 3.5 wt %, or about 0.1 wt % to 3.0 wt %, or about 0.5 wt % to 5.0 wt %, or about 1.0 wt % to 5.0 wt %, or about 1.5 wt % to 5.0 wt %, or about 2.0 wt % to 5.0 wt %, based on the total weight of the w/o latex.

The inversion agent is added to a latex at an inversion surfactant:inversion agent wt:wt ratio of about 10:1, or about 7.5:1, or about 5:1, or about 2.5:1, or about 2:1, or about 1.75:1, or about 1.5:1, or about 1.25:1, or about 1:1, or about 1:10, or about 1:7.5, or about 1:5, or about 1:2.5, or about 1:2, or about 1:1.75, or about 1:1.5, or about 1:1.25.

The inversion surfactant and inversion agent are added to a latex in a combined amount ([inversion surfactant+inversion agent]) of about 0.1 wt % to 20.0 wt % based on the total weight of the w/o latex, or about 0.5 wt % to 18.0 wt %, or about 1.0 wt % to 16.0 wt %, or about 1.5 wt % to 14.0 wt %, or about 2.0 wt % to 12.0 wt %, or about 2.5 wt % to 10.0 wt %, or about 3.0 wt % to 8.0 wt %, or about 3.5 wt % to 7.5 wt %, or about 4.0 wt % to 7.0 wt %, or about 4.5 wt % to 6.5 wt %, or about 0.1 wt % to 18.0 wt %, or about 0.1 wt % to 16.0 wt %, or about 0.1 wt % to 14.0 wt %, or about 0.1 wt % to 12.0 wt %, or about 0.1 wt % to 10.0 wt %, or about 0.1 wt % to 8.0 wt %, or about 0.1 wt % to 7.5 wt %, or about 0.1 wt % to 7.0 wt %, or about 0.1 wt % to 6.5 wt %, or about 0.5 wt % to 20.0 wt %, or about 1.0 wt % to 20.0 wt %, or about 1.5 wt % to 20.0 wt %, or about 2.0 wt % to 20.0 wt %, or about 2.5 wt % to 20.0 wt %, or about 3.0 wt % to 20.0 wt %, or about 3.5 wt % to 20.0 wt %, or about 4.0 wt % to 20.0 wt %, or about 4.5 wt % to 20.0 wt %, or about 5.0 wt % to 20.0 wt %, or about 5.5 wt % to 20.0 wt %, or about 6.0 wt % to 20.0 wt %, or about 6.5 wt % to 20.0 wt %, or about 7.0 wt % to 20.0 wt %, or about 7.5 wt % to 20.0 wt %, or about 8.0 wt % to 20.0 wt %, based on the total weight of the w/o latex.

Invertible Latices

Addition of an inversion agent of the present disclosure to a conventional w/o latex in the presence of an inverting surfactant, results in an invertible latex of the invention. The inversion agents may be added to the w/o latex before or after polymerization. The inversion agents may be added to a w/o latex before or after addition of an inverting surfactant. In some embodiments, the inversion agents are characterized as not being surfactants, that is, they are not surface active. Thus, in some embodiments, the invertible latices of the invention comprise, consist essentially of, or consist of a conventional w/o latex as described above, an inversion surfactant, and an inversion agent. In embodiments, the inversion agent is added to the w/o latex before polymerizing the monomer via a conventional free-radical or redox initiation. In other embodiments, the inversion agent is added directly to the w/o latex after polymerization is complete.

The invertible latices of the invention are stable or even shelf stable. That is, the invertible latices do not exhibit any observed signs of gross phase separation, coagulation, or precipitation for at least 24 hours at ambient laboratory temperatures. In embodiments, the invertible latex is stable under common ambient conditions for at least 1 day at 20° C.-25° C., or for at least 2 days at 20° C.-25° C., or for at least 1 week at 20° C.-25° C., or for at least 2 weeks at 20° C.-25° C., or for at least 1 month at 20° C.-25° C., or for at least 2 months at 20° C.-25° C., or for at least 1 day at 50° C., or for at least 2 days at 50° C., or for at least 5 days at 50° C., or for at least 10 days at 50° C., or for at least 30 days at 50° C.

Inversion of the Invertible Latices

The invertible latices of the invention invert rapidly and completely when contacted with a water source having high temperature, high total dissolved solids, or both to yield a polymer flooding solution. Numerous advantages are realized by use of the invertible latices of the invention; principal of these is the time savings realized when rapid and complete inversion replaces multi-step, slow, or incomplete inversion in the field. Both the invertible latices and the resulting polymer flooding solutions are characterized by the absence of the manifestations of latex or inversion instability; avoiding latex or inversion instability prevents downtime in the field necessitated by plugged or fouled equipment and avoids damages to reservoirs and plugging the formation.

During inversion, a water source is contacted with an invertible latex in one or more steps including one or more mixing and/or shearing processes to result in a polymer flooding solution having 1 wt % polymer or less. In some embodiments, the invertible latices of the invention provide for a simple, one-step inversion process characterized by absence of instabilities manifested as coagulation or precipitation of polymer or gross phase separation of the water phase from the oil phase prior to dissolution. It is a feature of the invention that the invertible latices of the invention provide for a simple, one-step inversion process in the presence of water sources contacted with the invertible latex at temperatures of about 30° C. to 100° C., or about 40° C. to 100° C., or about 50° C. to 100° C., or about 60° C. to 100° C. It is a feature of the invention that the invertible latices of the invention provide for a simple, one-step inversion process in the presence of water sources contacted with the invertible latex wherein the water source contacting the invertible latex includes about 0.1 to 30 wt % total dissolved solids. It is a feature of the invention that the invertible latices of the invention provide for a simple, one-step inversion process wherein the water source contacting the invertible latex includes about 0.1 to 30 wt % total dissolved solids and further contacts the inversion composition at about 30° C. to 100° C.

During the inversion process, the presence of the inversion agent reduces or prevents the coagulation of the polymer in the polymer flooding solution; reduces or prevents “hardening” or “raincycle” (evaporation, condensation) during storage that leads to formation of viscous masses on the surface and in the bulk; and prevents formation of lumps, skin, crust, or “waxing” due to the sensitivity of the invertible latex to shear during the pumping, filtration and stirring steps to which the latices are subjected in EOR applications, which in turn leads to the breakage of the mechanical seals of the pumps or the plugging of the filters, valves and check valves.

The polymer flooding solution typically includes about 1 wt % or less of polymer, other (residual) compounds from the inverted latex, and any dissolved solids present in the water source. The polymer flooding solutions of the invention are characterized by absence of gel particles, absence of gross phase separation, and/or absence other manifestations of inversion instability of w/o latices.

Inversion of the invertible latices to form the polymer flooding solutions is accomplished using conventional techniques and equipment, which is an unexpected benefit of employing the inversion agent of the invention using water sources that are high temperature, high total dissolved solids, or both high temperature/high total dissolved solids water sources. In some embodiments, inversion of invertible latices to form the polymer flooding solutions is suitably accomplished in a single step including dilution and mixing of the invertible latex with the water source to the target polymer concentration in the polymer flooding solution. In other embodiments, inversion of invertible latices to form the polymer flooding solutions is suitably accomplished in two dilution/mixing steps to reach the target polymer concentration. In some embodiments, the inversion and dilution to a target concentration of less than 1 wt % is accomplished in about 1 to 15 minutes, for example about 1 to 14, 1 to 13, 1 to 12, 1 to 11, 1 to 10, 1 to 9, 1 to 8, 1 to 7, 1 to 6, 1 to 5, 2 to 15, 3 to 15, 4 to 15, 5 to 15, 6 to 15, 7 to 15, 8 to 15, 9 to 15, 10 to 15, 2 to 10, 2 to 9, 2 to 8, 3 to 10, 3 to 9, 3 to 8, 4 to 10, 4 to 9, 4 to 8, or 4 to 7 minutes.

After inversion, the polymer flooding solutions comprise about 100 ppm to 10,000 ppm (0.01 wt % to 1.00 wt %) polymer, or about 200 ppm to 5000 ppm, or about 200 ppm to 4000 ppm, or about 200 ppm to 3000 ppm, or about 200 ppm to 2500 ppm polymer. In some embodiments the water source contacts the invertible latex at a temperature of about 30° C. to 100° C., or about 40° C. to 100° C., or about 50° C. to 100° C., or about 60° C. to 100° C. In other embodiments, the water source includes about 0.1 to 30 wt % total dissolved solids. In still other embodiments, the water source includes about 0.1 to 30 wt % total dissolved solids and further contacts the inversion composition at about 30° C. to 100° C.

A water source is water or a water solution having up to about 30.0 wt % total dissolved solids (TDS), or about 0.1 wt % to 29.0 wt %, or about 0.5 wt % to 28.0 wt %, or about 1.0 wt % to 27.0 wt %, or about 2.0 wt % to 25.0 wt %, or about 3.0 wt % to 20.0 wt % TDS. “High TDS” water sources have TDS of at least about 1 wt %. Thus in embodiments a water source includes one or more dissolved solid materials including but not limited to salts, ions, buffers, acids, bases, surfactants, compounds employed in the water used in mining operations, or other dissolved, dispersed, or emulsified compounds, materials, components, or combinations thereof. Nonlimiting examples of water sources include hard water, produced water from mining operations, brackish water, sea water, municipal waste water, tap water, “gray water”, and the like. Water sources having high TDS and high temperature are often encountered in use for EOR applications. For example, hydraulic fracturing and conventional oil recovery often results in produced water having high TDS, temperatures in excess of 60° C., or both; rather than use fresh water, in such situations it is economical to reuse the produced water as the water source for inversion processes.

In some embodiments, the method of inverting the invertible latices involves conventional inverting equipment. While inverting a latex is often accomplished in the field using high shear, stepwise dilution for efficiency in achieving full dilution and hydration of a polymer at the desired use level, we have found that relatively low shear mixing is advantageous in some embodiments for inverting the invertible latices of the invention. Such techniques are advantageous because avoiding some or all shear on the polymer chains during dissolution results in a higher final viscosity of the polymer flooding solution by reducing or eliminating chain scission of the high molecular weight polymers. It is a feature of the invertible latices of the invention that low-shear techniques that avoid substantial amounts of chain scission are suitably used in rapid inversion to result in polymer flooding solutions characterized by lack of manifestations of instability as discussed above.

Low shear inverting equipment employed to invert the invertible latices of the invention include static mixers. For example, U.S. Pat. No. 8,383,560 describes an apparatus employing a two-step inversion apparatus. In the first step, a w/o polymer latex is diluted to yield a polymer solution having about 5000 ppm to 20,000 ppm polymer solids employing a first static mixer having a pressure drop of at least 2 bars between the inlet and outlet thereof. In the second step, the partially diluted latex is applied to a second static mixer having a pressure drop of at least 1 bar between the inlet and outlet, and is further diluted to result in a polymer solution having between 500 and 3000 ppm, in practice between 1000 and 2000 ppm polymer solids. Such a two-step dilution system is usefully employed in conjunction with the invertible latices of the present invention. Conventional static mixers, as described in U.S. Pat. No. 8,383,560 are usefully employed; other low shear mixers and pumps are used in addition to, or as a replacement for, one or more static mixers described in U.S. Pat. No. 8,383,560.

Unexpectedly, we have further found that it is possible to employ a single stage inversion of the invertible latices by employing the inversion agents of the invention: that is, a single dilution step with a water source is usefully employed to dilute the invertible latices to form a polymer flooding solution at the final use concentration of about 100 ppm to 10,000 ppm. No intermediate or step-down dilution is required to form the polymer flooding solution. The polymer flooding solutions of the invention are characterized by the substantial absence of gels and solution instabilities in the field. This finding is significant because conventional w/o latices, subjected to a single dilution step in the field, result in substantial gel particles and/or solution instabilities that cause plating out or plugging of equipment used to carry out EOR by polymer flooding. Conventional water-in-oil EOR latices require two or more dilution steps and several hours to complete inversion to result in a polymer solution.

In some embodiments, after the invertible latices are contacted with water source to form a polymer flooding solution in a single dilution step, the polymer continues to build viscosity for about 0.5 minute to 120 minutes, or about 0.75 minute to 115 minutes, or about 1 minute to 110 minutes, or about 2 minutes to 105 minutes, or about 5 minutes to 100 minutes, or about 10 minutes to 90 minutes, or about 15 minutes to 80 minutes, or about 5 minutes to 70 minutes, or about 10 minutes to 70 minutes, or about 20 minutes to 70 minutes, or about 30 minutes to 70 minutes, or about 40 minutes to 70 minutes, or about 50 minutes to 70 minutes, or about 5 minutes to 60 minutes, or about 10 minutes to 60 minutes, or about 20 minutes to 60 minutes, or about 30 minutes to 60 minutes, or about 40 minutes to 60 minutes.

The inverted w/o latices, that is, the polymer flooding solutions of the invention, are characterized by a substantial freedom from gel particles and subsequent final polymer solution instability. The test for gel particle formation consists of measuring the time taken to filter given masses of solution containing 1000 ppm (0.1 wt %) polymer. The solution is contained in a steel bell filter ratio housing pressurized to and maintained at 20 psi. The filter has a diameter of 90 mm and a pore size of 5 microns.

The times required to obtain 90 g (t90 g); 120 g (t120 g); 180 g (t180 g) and 210 g (t210 g) of filtrate are therefore measured and a filtration quotient (or filter ratio denoted “FR”) is defined, expressed as:

${FR} = \frac{{{\,^{t}210}\mspace{14mu} g} - {{\,^{t}180}\mspace{14mu} g}}{{{\,^{t}120}\mspace{14mu} g} - {{\,^{t}90}\mspace{14mu} g}}$

The time measurement accuracy is 0.1 second.

The FR thus represents the capacity of the polymer solution to plug the filter for two equivalent consecutive mass samples. A typical acceptability criterion of the industry is FR<1.5. Conventional w/o latices employed for formation of polymer flooding solutions cannot achieve this level of filterability even after several hours of stirring in the laboratory. However, the invertible latices of the invention are characterized in that FR<1.5 is suitably achieved in about 5 minutes or less when a water source is contacted with a invertible latex of the invention, for example about 1 to 5 minutes, or about 2 to 5 minutes, or about 3 to 5 minutes, or about 4 to 5 minutes, or about 1 to 4 minutes, or about 1 to 3 minutes.

In a nonlimiting example of an EOR application, a w/o latex is applied to a reservoir as follows. An invertible latex is introduced to a mixing apparatus, wherein a water source is contemporaneously introduced into the apparatus in an amount suitable to form a polymer solution of the desired concentration. A water source, such as a high temperature water source, a high total dissolved solids water source, or a high temperature/high total dissolved solids water source is added to the invertible latex in an amount suitable to target the selected final polymer concentration. The water source is added prior to or contemporaneously with the carrying out of one or more mixing processes to thoroughly mix the invertible latex with the water source and accomplish the inversion.

In some embodiments, inversion of the invertible latices is suitably carried out using conventional equipment and methods used to invert latices in the field. Employing conventional equipment and methods familiar to those of skill in inverting w/o latices for EOR applications, it is possible to invert the invertible latex in less than 5 minutes, for example about 1 second to 5 minutes, or about 20 seconds to 5 minutes, or about 30 seconds to 5 minutes, or about 1 minute to 5 minutes, or about 2 minutes to 5 minutes, or about 1 second to 4 minutes, or about 1 second to 3 minutes, or about 1 second to 2 minutes, or about 1 second to 1 minute.

In some embodiments, inversion is suitably carried out by subjecting the invertible latices of the invention to a single-step inversion by diluting the latices with a water source and efficiently mixing the water source and the invertible latex in a single step. Devices suitable to achieve a one-step inversion include static mixers, paddle or blade mixers, mixing pumps, and the like. Any devices conventionally employed for w/o latex inversion are suitably employed to invert the invertible latices of the invention.

While the foregoing description is centered on EOR applications, water soluble polymers and latices thereof are also usefully employed in one or more papermaking applications using a Fourdrinier or inclined Fourdrinier apparatus, wherein water-based furnishes dispensed onto a wire can include an EOR-type polymer to improve the rheological profile of the furnish as dictated by machine or application parameters. In such applications, the invertible latices of the invention are advantageously employed due to rapid inversion upon addition to a furnish (a water-based dispersion of fibers) to result in a polymer solution similar to the polymer flooding solutions as described above. In papermaking applications, it is desirable to use tap water or another water-based solution to form the furnish and the w/o latices of the invention are suitable for use with water-based furnishes employing water-based solutions having high TDS, at elevated temperatures, or both. Papermaking includes making paper—that is, cellulose based mats—as well as other nonwoven fibrous mats such as filtration media that employ e.g. thermoplastic and glass fibers in addition to or instead of cellulose based fibers. One of skill will appreciate that other industrial uses, such as in wastewater treatment, mining services, or energy services, of the w/o latices of the invention are similarly envisioned.

EXAMPLES Abbreviations

CMPG—Carboxymethyl polyglycerol

CMG—Carboxymethyl glycerol

NHSI—N-hydroxysuccinimide

Example 1

Carboxymethyl glycerol used in the following examples was synthesized by adding 37.00 g of glycerol to a round bottom flask, followed by addition of 80.36 g of 50% NaOH with agitation. After mixing for 15 minutes at ambient temperature, 175.86 g of sodium chloroacetate were added to the mixture slowly while mixing, and the resulting mixture was mixed for at least 1 hour until the carboxymethylation reaction was completed. The product was neutralized with sulfuric acid prior to the invertibility analysis of Example 6.

Example 2

Carboxymethyl polyglycerols used in the following examples were synthesized according to the procedure of Example 1 with the following modifications. Branched polyglycerols were synthesized according to the procedure described in U.S. Patent Application Publication No. 2011/0092743 A1, which is incorporated by reference herein in its entirety. Thus, 64.28 g of a branched polyglycerol was dissolved in 19.28 g of deionized water. 23.32 g of 50% NaOH and 28.30 g of sodium chloroacetate were used for the carboxymethylation reaction.

Example 3

Water-in-oil latices were prepared using the components of Table 1.

TABLE 1 Components of w/o latices. Material Wt % Water Phase Acrylamide 49.5% 38.2953 DI water 15.0941 Acrylic acid 7.6437 Sodium hydroxide 8.2524 Sodium formate 0.0340 VERSENEX ® 80 (pentasodium 0.0300 diethylenetriaminepentaacetate) Oil Phase Hydrocarbon solvent (hydrotreated light distillate) 27.1845 Sorbitan sesquioleate (Span 83 ™ or Arlacel 83 ™, Croda 0.8234 International PLC, Yorkshire, United Kingdom) Polyoxyethylene (40-50) sorbitol hexaoleate 2.5747 HYPERMER ® B210 (Croda International PLC, Yorkshire, 0.0194 United Kingdom) Initiator 2,2′-azobisisobutyronitrile 0.0288 Post treatment/reduction of acrylamide residual TBHP (tertiary butyl hydroperoxide) 70% 0.0064 Sodium metabisulfite 0.0133

Polymerization of the components of Table 1 was conducted at 38° C. to 44° C. for 3 to 4 hours and post heated for 57° C. for 30 minutes. The latex polymer (an acrylic acid and acrylamide copolymer) was then agitated at 800 rpm using a cage stirrer at room temperature. A carbonyl functional inversion agent (2-3 wt %, neutralized to pH 7), then a stabilizer (ammonium thiocyanate, 0.125%), and then an inverting surfactant (tridecyl alcohol ethoxylate (TDA-12; ethoxylated C11-14-ISO-, C13-rich alcohol; T-DET® A 1312; Harcros, Kansas City, Kans.), 3.3%) were added with agitation. Control latices did not include an inversion agent. The resulting blend was stirred at room temperature for 30 minutes to produce a w/o latex for the invertibility analysis of Example 7.

Example 4

The stability of the w/o latices produced in Example 3 was evaluated and stability data is presented in Table 2. Stability was assessed by allowing the latices to stand at ambient laboratory temperatures for the indicated amount of time, and the amount of oil phase that separates from the latex (oil split) was observed as an indication of latex stability; the bulk viscosity (BV) of the lattices was also measured before and after standing.

TABLE 2 Stability data of the w/o latices of Example 3. Inversion Agent Oil Split Latex BV Latex BV Aging (3 wt %) (%) (initial, cP) (Final, cP) Time Lactic acid 7.46 824 900 2.5 months Malic acid 4.54 840 956 2.5 months

The stability data presented in Table 2 demonstrates that w/o latices comprising α-hydroxy carboxylic acid inversion agents remained stable after 2.5 months. The oil split was low and no significant change in the latex BV was observed.

Example 5

Water-in-oil latices were prepared using the components of Table 3.

TABLE 3 Components of w/o latices. Material Wt % Acrylamide 49.5% 38.2953 DI water 13.1717 Acrylic acid 7.6437 Sodium hydroxide 50% 8.3457 Sodium formate 0.0340 Glyoxal 40% 0.0117 VERSENEX ® 80 (pentasodium 0.0300 diethylenetriaminepentaacetate) Hydrocarbon solvent (hydrotreated light distillate) 29.0000 Sorbitan sesquioleate 0.8892 Polyoxyethylene (40-50) sorbitol hexaoleate 2.5108 HYPERMER ® B210 (Croda International PLC, Yorkshire, 0.0194 United Kingdom) 2,2′-azobisisobutyronitrile 0.0288 TBHP (tert-butyl hydroperoxide) 70% 0.0064 Sodium metabisulfite 0.0133

The w/o latices were prepared as in Example 3. The stability of the w/o latices was evaluated and stability data is presented in Table 4. Stability was assessed by placing the latices in a 50° C. oven for 4.5 months, and the amount of oil phase that separates from the latex (oil split) was observed as an indication of latex stability; the bulk viscosity (BV) of the lattices was also measured before and after standing.

TABLE 4 Stability data of the w/o latices of Table 3. Inversion Inversion Oil Split Latex BV Latex BV Agent (2 wt %) Agent (1 wt %) (%) (initial, cP) (Final, cP) Carboxymethyl Lactic acid 19.05 816 1156 polyglycerol 2 Polyglycerol 2 Lactic acid 14.63 812 988

The stability data presented in Table 4 demonstrates that w/o latices comprising carbonyl functional inversion agents remained stable after 4.5 months.

Example 6

The bulk viscosity (BV) of each of the w/o latices produced in Example 3 was measured at room temperature using a Brookfield DV-E viscometer.

Example 6A

BV data for w/o latices comprising 3 wt % of a carbonyl functional inversion agent are presented in Table 5.

TABLE 5 Bulk viscosity (BV) data of w/o latices of Example 3 comprising 3 wt % of a carbonyl functional inversion agent. Inversion Agent (3 wt %) MW of polyglycerols (Da) BV (cps) None (Control) N/A 2432 Glycerol N/A 2152 Carboxymethyl polyglycerol 1 260 1892 Carboxymethyl polyglycerol 2 960 1736 Carboxymethyl glycerol N/A 780

The data of Table 5 demonstrate that the w/o latices of Example 3 comprising 3 wt % of a carbonyl functional inversion agent had bulk viscosities lower than w/o latices comprising no inversion agent (control SC latices) and lower than w/o latices comprising 3 wt % glycerol. The inclusion of a carbonyl functional inversion agent in w/o latices decreased bulk viscosity 22% to 68% over control latices and 12% to 64% over w/o latices comprising glycerol. The inclusion of 3 wt % glycerol in w/o latices had a negligible effect on bulk viscosity. The lower BVs of the w/o latices comprising a carbonyl functional inversion agent provide better pumpability for pumping and transferring the invertible latices.

Example 6B

BV data for w/o latices comprising 3 wt % of a carbonyl functional inversion agent are presented in Table 6.

TABLE 6 Bulk viscosity data of w/o latices of Example 3 comprising 3 wt % of a carbonyl functional inversion agent. Inversion Agent (3 wt %) BV (cps) None (Control) 2432 Glycerol 2152 Glycolic acid 1292 Lactic acid 824 Malic acid 840

The data of Table 6 demonstrate that the w/o latices of Example 3 comprising 3 wt % of a carbonyl functional inversion agent have bulk viscosities lower than w/o latices comprising no inversion agent (control w/o latices) and lower than w/o latices comprising 3 wt % glycerol. The inclusion of a carbonyl functional inversion agent in w/o latices decreased bulk viscosity 47% to 66% over control latices and 40% to 62% over w/o latices comprising glycerol. The inclusion of 3 wt % glycerol in w/o latices had a negligible effect on bulk viscosity. The lower BVs of the w/o latices comprising a carbonyl functional inversion agent provide better pumpability for pumping and transferring the invertible latices.

Example 6C

BV data for w/o latices comprising 3 wt % of an carbonyl functional inversion agent are presented in Table 7.

TABLE 7 Bulk viscosity data of w/o latices of Example 3 comprising 3 wt % of an carbonyl functional inversion agent. Inversion Agent (3 wt %) BV (cps) None (Control) 2432 Glycerol 2152 N-hydroxysuccinimide 1656 Glycine 2048

The data of Table 7 demonstrate that the w/o latices of Example 3 comprising 3 wt % of an carbonyl functional inversion agent have bulk viscosities lower than w/o latices comprising no inversion agent (control w/o latices) and lower than w/o latices comprising 3 wt % glycerol. The inclusion of a carbonyl functional inversion agent in w/o latices decreased bulk viscosity 16% to 32% over control latices and 5% to 23% over w/o latices comprising glycerol. The inclusion of 3 wt % glycerol in w/o latices had a negligible effect on bulk viscosity. The lower BVs of the w/o latices comprising an carbonyl functional inversion agent provide better pumpability for pumping and transferring the invertible latices.

Example 6D

BV data for w/o latices of Example 3 comprising 2 wt % of a carbonyl functional inversion agent are presented in Table 8.

TABLE 8 Bulk viscosity data of w/o latices of Example 3 comprising 2 wt % of a carbonyl functional inversion agent. Inversion Agent (2 wt %) MW of polyglycerols (Da) BV (cps) None (Control) N/A 2432 Glycerol N/A 2084 Carboxymethyl polyglycerol 1 260 840 Carboxymethyl polyglycerol 2 960 780 Carboxymethyl glycerol N/A 544 Lactic acid N/A 890

The data of Table 8 demonstrate that the w/o latices of Example 3 comprising 2 wt % of a carbonyl functional inversion agent have bulk viscosities lower than w/o latices comprising no inversion agent (control w/o latices) and lower than w/o latices comprising 2 wt % glycerol. The inclusion of a carbonyl functional inversion agent in w/o latices decreased bulk viscosity from 63% to 78% over control latices and from 57% to 74% over w/o latices comprising glycerol. The inclusion of 2 wt % glycerol in w/o latices had no effect on bulk viscosity. The lower BVs of the w/o latices comprising a carbonyl functional inversion agent provide better pumpability for pumping and transferring the invertible latices.

Example 7

The invertibility of the w/o latices of Example 3 was determined by torque monitor technique. A torque monitor is a qualitative analytical tool comprising a DC stir motor, a controller that can report the torque (DC voltage) required to maintain a constant stir speed, and a computer to record the torque reading as a function of time. In a typical experiment, the w/o latex was added to a stirring solution of 3.5% synthetic sea water (Glas-Col Precision Stirrer, obtained from Glas-Col LLC of Terre Haute, Ind.), and the generated torque was monitored as a function of time ([polymer]=10000 ppm, 400 rpm). The analysis was run for 20-30 min to confirm the torque remained stable. Experiments were conducted at 60° C. with high salinity conditions to evaluate the performance of w/o latices under high stress conditions.

The 3.5% synthetic seawater used in the present Example was formed by blending the components of Table 9.

TABLE 9 Components of 3.5% synthetic seawater. Reagent Amount (g) Deionized water 957.99 Sodium bicarbonate (NaHCO₃) 0.01 Calcium chloride CaCl₂•2H₂O 1.57 Sodium sulfate (Na₂SO₄) 4.38 Magnesium chloride (MgCl₂•6H₂O) 11.39 Sodium chloride (NaCl) 24.65

Example 7A

Torque data at 60° C. for w/o latices comprising 3 wt % of a carbonyl functional inversion agent are presented in Table 10 and FIG. 1.

TABLE 10 Torque data at 60° C. of w/o latices of Example 3 comprising 3 wt % of a carbonyl functional inversion agent. Torque (g · cm) Time (sec) Control Glycerol CMPG 1 CMPG 2 CMG 0 −0.3713 0.5544 1.1800 0.1170 0.7019 20 13.7685 101.3641 138.2039 101.6388 172.8210 40 116.7145 162.0941 308.3903 215.3676 293.8741 60 164.8305 173.2839 324.6663 293.2892 314.1174 80 185.1756 187.7289 328.1250 292.6788 351.0437 100 191.3808 214.5844 384.4808 343.0328 335.0728 120 169.1030 234.2173 376.5462 325.3326 352.6713 140 209.6914 197.4945 359.0495 330.5206 342.3971 160 234.4106 202.4790 326.0905 338.8621 339.4470 180 193.4153 206.8532 388.4481 363.9882 340.6677 200 216.6087 227.8086 379.6997 330.0120 376.0681 220 255.1626 236.2518 350.1994 326.8585 354.2989 240 250.9918 273.1781 335.0423 337.2345 360.5042 260 222.6105 295.9646 318.9697 295.1202 333.2418 280 234.8175 309.6975 383.5653 365.8193 357.9610 300 284.1543 336.4512 366.9840 292.1702 329.9866 320 329.1168 318.1407 347.8597 371.0073 326.8331 340 346.0032 334.3150 326.9043 305.0893 321.6451 360 319.2495 331.9753 339.0096 299.7996 327.5452 380 385.7778 344.6910 364.0340 320.2464 342.4988 400 377.5380 403.3864 360.6771 299.5962 300.6897 420 286.7991 358.5256 319.6818 293.5944 314.2192 440 381.7088 329.0253 317.8507 300.6134 325.1038 460 363.2965 330.0425 370.5444 346.4915 354.1972 480 370.2138 378.7689 338.2975 338.7604 332.7332 500 325.6582 329.0253 305.9489 335.9121 321.2382 520 377.1311 341.2323 350.4028 294.8151 332.8349 540 361.9741 329.6356 336.5682 324.7223 325.9176 560 319.4529 339.1978 299.7437 305.8014 358.8765 580 373.4690 322.8200 344.5028 315.2618 356.1300 600 321.2840 323.2269 310.6283 322.5861 350.3316 620 374.3846 360.0515 307.6782 298.8841 360.1990 640 356.5826 313.8682 336.4665 356.9692 366.2008 660 350.2757 355.6773 315.6128 300.3082 337.9211 680 312.6373 371.1395 330.2612 292.7806 312.2864 700 311.2132 335.4340 316.2231 299.4944 314.7278 720 363.0931 287.2162 305.3385 304.2755 342.7022 740 320.2667 376.8361 320.8008 308.1411 344.6350 760 331.9651 347.3358 301.4730 290.0340 353.0782 780 332.4738 320.6838 350.9115 374.4659 337.4125 800 370.0104 355.4738 302.2868 311.9049 357.5541 820 348.7498 354.4566 319.7835 309.7687 320.5261 840 326.3702 324.5494 315.5111 299.3927 321.2382 860 342.9515 330.9580 295.5729 292.1702 319.8140 880 368.9931 337.8754 304.4230 294.2047 349.1109 900 354.7516 343.6737 325.1750 326.3499 318.2882 920 307.4493 305.6285 303.4058 293.1875 314.1174 940 309.5856 309.7992 309.8145 286.4736 352.4679 960 309.4838 333.3995 323.5474 292.6788 341.3798 980 366.4500 345.8099 297.0988 290.8478 317.1692 1000 347.3256 358.9325 305.5420 288.7115 316.9657 1020 306.6355 351.2014 329.6509 289.2202 311.1674 1040 366.3483 307.8664 297.7091 331.3344 306.3863 1060 294.9371 357.8135 346.2321 294.2047 324.9003 1080 302.1596 331.6701 295.5729 311.7015 303.1311 1100 324.0306 342.8599 293.0298 314.1429 305.0639 1120 299.3113 350.2858 289.5711 282.6080 308.2174 1140 331.9651 343.2668 285.9090 236.1196 326.7314 1160 338.6790 350.8962 296.9971 297.7651 302.8259 1180 358.3120 360.4584 318.3594 287.1857 305.1656 1200 329.7272 320.0734 287.6383 280.2684 287.9740

The data of Table 10 and FIG. 1 demonstrate that the w/o latices of Example 3 comprising 3 wt % of a carbonyl functional inversion agent invert faster than w/o latices comprising no inversion agent (control w/o latices) at 60° C. in 3.5% SSW and faster than w/o latices comprising 3 wt % glycerol at 60° C. in 3.5% SSW. The data of Table 10 and FIG. 1 also demonstrate that the w/o latices of Example 3 comprising 3 wt % of a carbonyl functional inversion agent invert to a greater extent than w/o latices comprising no inversion agent (control w/o latices) at 60° C. in 3.5% SSW and to a greater extent than w/o latices comprising 3 wt % glycerol at 60° C. in 3.5% SSW. The faster inversion rates and greater extent of inversion of the w/o latices comprising a carbonyl functional inversion agent provide better performance of the invertible latices than control w/o latices and w/o latices comprising glycerol under high stress conditions such as high TDS and elevated temperature.

Example 7B

Torque data at 60° C. for w/o latices comprising 3 wt % of a carbonyl functional inversion agent are presented in Table 11 and FIG. 2.

TABLE 11 Torque data at 60° C. of w/o latices of Example 3 comprising 3 wt % of a carbonyl functional inversion agent. Torque (g · cm) Time Malic (sec) Control Glycerol Glycolic Acid Lactic Acid Acid 0 −0.3713 0.5544 1.0071 −0.9104 −0.1526 20 13.7685 101.3641 96.4254 132.1462 113.3728 40 116.7145 162.0941 197.4386 232.7525 204.6204 60 164.8305 173.2839 235.8907 294.0928 213.0636 80 185.1756 187.7289 276.2756 284.4289 248.4639 100 191.3808 214.5844 277.6998 281.3772 259.1451 120 169.1030 234.2173 308.8277 321.9655 268.6056 140 209.6914 197.4945 291.7379 344.1416 304.7180 160 234.4106 202.4790 308.5225 300.6032 293.5282 180 193.4153 206.8532 292.2465 365.7074 311.8388 200 216.6087 227.8086 294.8914 344.0399 308.6853 220 255.1626 236.2518 314.7278 356.2469 282.0333 240 250.9918 273.1781 322.0520 349.6348 311.0250 260 222.6105 295.9646 334.6659 353.8055 310.4146 280 234.8175 309.6975 301.3000 332.3415 317.9423 300 284.1543 336.4512 313.1002 320.7448 329.6407 320 329.1168 318.1407 311.7778 357.8746 323.9441 340 346.0032 334.3150 301.4018 361.7401 306.5491 360 319.2495 331.9753 320.8313 374.0489 317.0268 380 385.7778 344.6910 312.4898 369.9799 315.1957 400 377.5380 403.3864 325.8158 355.9418 318.2475 420 286.7991 358.5256 321.0347 359.8073 343.8822 440 381.7088 329.0253 310.1501 324.8138 327.0976 460 363.2965 330.0425 299.4690 314.8448 324.3510 480 370.2138 378.7689 315.0330 325.4242 334.3201 500 325.6582 329.0253 286.0413 372.6247 259.5520 520 377.1311 341.2323 293.9758 364.1815 302.7852 540 361.9741 329.6356 327.4434 363.9781 309.9060 560 319.4529 339.1978 301.4018 362.1470 297.0886 580 373.4690 322.8200 293.3655 344.2434 282.6436 600 321.2840 323.2269 296.1121 315.1499 313.2629 620 374.3846 360.0515 288.5844 315.3534 304.9215 640 356.5826 313.8682 319.9158 343.5313 305.3284 660 350.2757 355.6773 298.8586 362.2487 312.4491 680 312.6373 371.1395 283.3964 336.3088 296.6817 700 311.2132 335.4340 283.3964 367.0298 322.8251 720 363.0931 287.2162 290.7206 326.5432 329.3355 740 320.2667 376.8361 309.3363 350.1434 306.8542 760 331.9651 347.3358 319.1020 361.9436 295.0541 780 332.4738 320.6838 318.3899 369.9799 311.3302 800 370.0104 355.4738 302.8259 332.0363 335.0321 820 348.7498 354.4566 303.4363 327.6622 315.0940 840 326.3702 324.5494 275.5636 313.8275 331.2683 860 342.9515 330.9580 291.9413 320.3379 304.4128 880 368.9931 337.8754 317.2709 328.7811 307.0577 900 354.7516 343.6737 282.7861 305.2826 313.9750 920 307.4493 305.6285 280.2429 347.4986 325.3682 940 309.5856 309.7992 310.0484 326.7466 329.3355 960 309.4838 333.3995 282.8878 327.2552 319.6716 980 366.4500 345.8099 302.6225 333.5622 326.5889 1000 347.3256 358.9325 320.7296 309.6568 295.9696 1020 306.6355 351.2014 272.0032 367.6402 332.9976 1040 366.3483 307.8664 292.6534 315.7603 305.0232 1060 294.9371 357.8135 309.7432 338.5468 254.8726 1080 302.1596 331.6701 294.2810 346.2779 296.7834 1100 324.0306 342.8599 277.6998 305.7912 294.3420 1120 299.3113 350.2858 282.2774 338.5468 290.8834 1140 331.9651 343.2668 271.9014 367.0298 296.8852 1160 338.6790 350.8962 284.9223 351.6693 307.9732 1180 358.3120 360.4584 271.6980 306.9102 290.3748 1200 329.7272 320.0734 310.5570 287.7858 305.4301

The data of Table 11 and FIG. 2 demonstrate that the w/o latices of Example 3 comprising 3 wt % of a carbonyl functional inversion agent invert faster than w/o latices comprising no inversion agent (control w/o latices) at 60° C. in 3.5% SSW and faster than w/o latices comprising 3 wt % glycerol at 60° C. in 3.5% SSW. The data of Table 11 and FIG. 2 also demonstrate that the w/o latices of Example 3 comprising 3 wt % of a carbonyl functional inversion agent invert to a greater extent than w/o latices comprising no inversion agent (control w/o latices) at 60° C. in 3.5% SSW and to a greater extent than w/o latices comprising 3 wt % glycerol at 60° C. in 3.5% SSW. The faster inversion rates and greater extent of inversion of the w/o latices comprising a carbonyl functional inversion agent provide better performance of the invertible latices than control w/o latices and w/o latices comprising glycerol under high stress conditions such as high TDS and elevated temperature.

Example 7C

Torque data at 60° C. for w/o latices comprising 3 wt % of an carbonyl functional inversion agent are presented in Table 12 and FIG. 3.

TABLE 12 Torque data at 60° C. of w/o latices of Example 3 comprising 3 wt % of an carbonyl functional inversion agent. Torque (g · cm) Time (sec) Control Glycerol NHSI Glycine 0 −0.3713 0.5544 0.0509 −0.2136 20 13.7685 101.3641 82.3466 32.8471 40 116.7145 162.0941 147.1456 119.2118 60 164.8305 173.2839 170.1355 152.4760 80 185.1756 187.7289 180.3080 184.1125 100 191.3808 214.5844 217.9464 147.7966 120 169.1030 234.2173 196.5841 151.1536 140 209.6914 197.4945 188.7512 177.3987 160 234.4106 202.4790 213.6739 182.6884 180 193.4153 206.8532 225.4740 169.4641 200 216.6087 227.8086 263.7227 223.6837 220 255.1626 236.2518 250.1933 246.9788 240 250.9918 273.1781 287.0178 211.3749 260 222.6105 295.9646 286.5092 242.0959 280 234.8175 309.6975 320.8923 268.2393 300 284.1543 336.4512 321.9096 266.4083 320 329.1168 318.1407 337.2701 313.9140 340 346.0032 334.3150 324.2493 287.9740 360 319.2495 331.9753 352.1220 297.2310 380 385.7778 344.6910 365.7532 290.0085 400 377.5380 403.3864 344.8995 343.8212 420 286.7991 358.5256 371.8567 312.7950 440 381.7088 329.0253 343.4753 346.6695 460 363.2965 330.0425 321.2992 302.8259 480 370.2138 378.7689 357.5134 328.6641 500 325.6582 329.0253 325.7751 348.9075 520 377.1311 341.2323 357.9203 315.5416 540 361.9741 329.6356 323.9441 304.3518 560 319.4529 339.1978 317.6371 308.9294 580 373.4690 322.8200 318.1458 321.4417 600 321.2840 323.2269 314.7888 293.6707 620 374.3846 360.0515 326.5889 340.9729 640 356.5826 313.8682 333.0994 286.4482 660 350.2757 355.6773 328.1148 292.2465 680 312.6373 371.1395 317.7389 341.0746 700 311.2132 335.4340 315.6026 334.0556 720 363.0931 287.2162 361.8876 307.0984 740 320.2667 376.8361 345.7133 296.8241 760 331.9651 347.3358 320.5872 295.8069 780 332.4738 320.6838 360.4635 334.2590 800 370.0104 355.4738 283.2540 307.3018 820 348.7498 354.4566 336.1511 290.3137 840 326.3702 324.5494 340.4236 308.9294 860 342.9515 330.9580 312.6526 334.4625 880 368.9931 337.8754 348.5616 309.9467 900 354.7516 343.6737 367.6860 330.8004 920 307.4493 305.6285 340.4236 292.4500 940 309.5856 309.7992 350.1892 320.1192 960 309.4838 333.3995 335.0321 316.0502 980 366.4500 345.8099 354.1565 314.1174 1000 347.3256 358.9325 340.8305 280.6498 1020 306.6355 351.2014 356.6996 294.5862 1040 366.3483 307.8664 346.1202 314.3209 1060 294.9371 357.8135 366.1601 331.8176 1080 302.1596 331.6701 355.3772 330.0883 1100 324.0306 342.8599 346.2219 279.6326 1120 299.3113 350.2858 363.7187 294.4845 1140 331.9651 343.2668 338.2874 321.4417 1160 338.6790 350.8962 373.3826 295.8069 1180 358.3120 360.4584 319.8751 300.6897 1200 329.7272 320.0734 287.7299 287.6689

The data of Table 12 and FIG. 3 demonstrate that some of the w/o latices of Example 3 comprising 3 wt % of an carbonyl functional inversion agent, such as NHSI, invert faster than w/o latices comprising no inversion agent (control w/o latices) at 60° C. in 3.5% SSW and as fast as w/o latices comprising 3 wt % glycerol at 60° C. in 3.5% SSW. The data of Table 12 and FIG. 3 also demonstrate that some of the w/o latices of Example 3 comprising 3 wt % of an carbonyl functional inversion agent, such as NHSI, invert to a greater extent than w/o latices comprising no inversion agent (control w/o latices) at 60° C. in 3.5% SSW and as completely as w/o latices comprising 3 wt % glycerol at 60° C. in 3.5% SSW. The comparable inversion rates and comparable extent of inversion of the w/o latices comprising an carbonyl functional inversion agent provide comparable performance of the invertible latices to w/o latices comprising glycerol under high stress conditions such as high TDS and elevated temperature.

Example 7D

Torque data at 60° C. for w/o latices comprising 2 wt % of a carbonyl functional inversion agent are presented in Table 13 and FIG. 4.

TABLE 13 Torque data at 60° C. of w/o latices of Example 3 comprising 2 wt % of a carbonyl functional inversion agent. Torque (g · cm) Time (sec) Control Glycerol CMPG 1 CMPG 2 CMG Lactic Acid 0 −0.3713 −0.3204 −0.7477 −0.1424 0.4832 1.1292 20 13.7685 55.9336 95.7896 95.3776 93.6635 93.2922 40 116.7145 109.1359 163.9455 194.2546 210.8510 141.3066 60 164.8305 140.1622 206.5684 226.7049 255.5084 166.1275 80 185.1756 145.2484 234.3394 250.0000 274.3276 167.5517 100 191.3808 149.8260 278.7933 278.4831 281.0415 207.3263 120 169.1030 157.5572 278.8951 280.7210 308.8125 187.1847 140 209.6914 167.6280 297.6125 304.0161 300.8779 218.1091 160 234.4106 198.5524 290.5935 318.0542 305.4555 210.1746 180 193.4153 203.1301 293.4418 305.8472 307.9987 202.4434 200 216.6087 179.1229 292.8314 309.9162 320.4091 226.9592 220 255.1626 210.5560 336.4716 293.2332 301.9969 241.9128 240 250.9918 239.5477 307.3781 287.2314 305.3538 240.0818 260 222.6105 209.6405 287.9486 332.0923 303.9296 231.5369 280 234.8175 239.5477 346.8475 328.5319 296.8089 246.3888 300 284.1543 245.0409 305.4454 308.0851 305.2521 278.5339 320 329.1168 230.4942 302.9022 307.3730 295.2830 274.8718 340 346.0032 274.9481 324.8749 300.1506 288.2640 286.8754 360 319.2495 281.1534 318.8731 297.5057 237.9100 272.8373 380 385.7778 287.7655 314.2955 302.4902 337.6007 282.0943 400 377.5380 273.2188 322.8404 275.5330 311.7625 297.2514 420 286.7991 282.3741 306.2592 298.2178 318.6798 291.0461 440 381.7088 296.1070 301.9867 306.7627 295.8934 322.0723 460 363.2965 314.1123 293.8487 293.9453 316.7470 342.7226 480 370.2138 298.3449 293.6452 289.0625 314.7125 338.7553 500 325.6582 293.4621 298.2229 278.5848 297.5210 309.6619 520 377.1311 308.1106 301.0712 299.4385 290.4002 309.1532 540 361.9741 316.3503 285.6089 306.8644 311.8642 305.6946 560 319.4529 299.6674 319.2800 297.6074 324.6816 297.6583 580 373.4690 307.3985 233.9325 310.0179 310.4401 297.1497 600 321.2840 294.1742 310.4299 289.2660 293.3502 332.1431 620 374.3846 328.0487 292.8314 300.1506 296.0968 306.5084 640 356.5826 303.4312 322.0266 295.2677 309.3211 312.1033 660 350.2757 320.3176 294.0521 302.6937 321.7316 300.7100 680 312.6373 329.6763 324.6714 323.5474 291.0105 338.7553 700 311.2132 307.0933 304.5298 310.5265 286.5346 334.1777 720 363.0931 331.9143 321.4162 286.6211 283.7880 300.2014 740 320.2667 320.4193 298.9349 304.7282 304.4383 318.7154 760 331.9651 313.5020 301.8850 290.7918 286.5346 309.3567 780 332.4738 285.9344 317.3472 290.7918 312.8815 296.4376 800 370.0104 326.7263 248.7844 304.7282 298.7417 307.2205 820 348.7498 252.4668 303.9195 288.5539 317.2557 299.8962 840 326.3702 293.5638 318.4662 294.1488 320.0022 335.9070 860 342.9515 296.0052 302.2919 293.2332 316.6453 305.1860 880 368.9931 314.2141 315.0075 325.7853 305.8624 330.1086 900 354.7516 295.2932 321.2128 322.9370 285.5174 337.0260 920 307.4493 301.7019 325.8921 311.2386 299.0468 297.7600 940 309.5856 286.5448 330.7749 292.9281 294.8761 299.4893 960 309.4838 280.6447 310.4299 310.8317 299.0468 336.5173 980 366.4500 297.1242 301.2746 286.4176 283.9915 295.2169 1000 347.3256 324.1831 309.2092 294.3522 311.3556 336.8225 1020 306.6355 290.4104 312.4644 239.6240 281.7535 306.3049 1040 366.3483 308.1106 284.1848 293.7419 301.4882 337.1277 1060 294.9371 285.7310 280.0140 293.9453 273.5138 321.1568 1080 302.1596 281.0516 310.9385 310.9334 301.9969 295.3186 1100 324.0306 276.7792 309.7178 300.6592 284.0932 332.6518 1120 299.3113 310.1451 310.6333 287.9435 309.8297 327.6672 1140 331.9651 303.5329 304.9367 281.9417 282.5673 307.6274 1160 338.6790 288.4776 299.5453 315.7145 285.5174 314.9516 1180 358.3120 294.9880 286.1176 276.3468 315.5263 317.5964 1200 329.7272 299.9725 315.9231 317.8507 288.3657 287.7909

The data of Table 13 and FIG. 4 demonstrate that the w/o latices of Example 3 comprising 2 wt % of a carbonyl functional inversion agent invert faster than w/o latices comprising no inversion agent (control w/o latices) at 60° C. in 3.5% SSW and faster than w/o latices comprising 2 wt % glycerol at 60° C. in 3.5% SSW. The data of Table 13 and FIG. 4 also demonstrate that the w/o latices of Example 3 comprising 2 wt % of a carbonyl functional inversion agent invert to a greater extent than w/o latices comprising no inversion agent (control w/o latices) at 60° C. in 3.5% SSW and to a greater extent than w/o latices comprising 2 wt % glycerol at 60° C. in 3.5% SSW. The faster inversion rates and greater extent of inversion of the w/o latices comprising a carbonyl functional inversion agent provide better performance of the invertible latices than control w/o latices and w/o latices comprising glycerol under high stress conditions such as high TDS and elevated temperature.

Example 8

The invertibility of the w/o latices of Example 3 was determined by torque monitor technique as described in Example 7 with the following modifications. Experiments were conducted at room temperature (ca 25° C.) or 4° C. to evaluate the performance of w/o latices across a range of temperatures.

Example 8A

Torque data at room temperate for w/o latices comprising 3 wt % of a carbonyl functional inversion agent are presented in Table 14 and FIG. 5.

TABLE 14 Torque data at room temperature of w/o latices of Example 3 comprising 3 wt % of a carbonyl functional inversion agent. Time Torque (g · cm) (sec) Control Glycerol CMPG 1 CMPG 2 0 −0.0712 −0.0865 −0.6358 −0.3713 20 2.0650 26.2604 104.3447 83.2469 40 141.0217 284.3374 325.6989 330.5410 60 295.6441 424.2096 318.3746 484.8582 80 382.3140 531.7332 477.3712 582.5144 100 475.9013 557.2662 447.0571 500.4222 120 447.4182 545.4661 455.3986 602.9612 140 488.6169 518.0003 569.5343 594.0094 160 518.6259 586.9700 489.9851 616.2872 180 498.6877 588.0890 568.0084 585.8714 200 511.0982 564.9974 512.4664 524.3276 220 472.0357 573.1354 480.0161 572.4436 240 460.8459 540.7867 565.9739 548.0296 260 472.7478 522.7814 490.0869 463.4959 280 427.8870 527.3590 569.0257 545.6899 300 450.1648 448.7254 437.2915 559.0159 320 449.4527 520.3400 383.7840 548.6399 340 447.7234 464.7980 567.8050 513.5447 360 438.5681 525.8331 513.8906 525.6500 380 450.5717 453.9134 507.7871 525.2431 400 439.2802 512.1002 553.4617 565.7298 420 431.0404 519.2210 476.6591 518.8344 440 448.0286 454.4220 501.3784 490.5548 460 422.9024 467.9515 553.4617 519.4448 480 431.0404 523.3917 480.5247 481.8064 500 429.2094 438.7563 457.6365 519.0379 520 457.8959 450.8616 433.6294 479.3650 540 426.4628 438.4511 456.1106 481.5013 560 397.8780 433.2631 391.6168 511.5102 580 406.8298 449.3357 430.2724 521.5810 600 438.3647 487.1775 419.6930 441.4215 620 399.5056 423.4975 423.0499 468.2770 640 397.5728 459.7117 448.3795 449.4578 660 392.2831 424.8199 418.3706 461.5631 680 407.2367 493.9931 540.2374 446.2026 700 413.1368 428.3803 488.4593 462.8855 720 421.6817 425.3286 448.5830 467.9718 740 381.5002 457.5755 413.5895 484.3496 760 380.0761 413.1215 458.7555 445.1853 780 399.6073 446.4874 409.2153 425.5524 800 375.0916 468.5618 452.3468 473.2615 820 412.6282 410.3750 408.7067 467.7684 840 438.6698 413.5284 491.4093 431.7576 860 370.6156 446.9961 515.8234 489.7410 880 398.7935 451.3702 404.7394 438.5732 900 374.2778 440.7908 475.2350 436.1318 920 406.1178 409.7646 408.6049 443.5577 940 397.3694 415.3595 480.4230 485.4685 960 373.3622 449.9461 419.6930 466.8528 980 366.4449 457.2703 398.4324 451.8992 1000 426.4628 405.4921 431.9000 478.4495 1020 407.4402 401.8300 375.4425 444.5750 1040 379.3640 410.1715 451.1261 446.3043 1060 432.7698 458.0841 444.6157 443.3543 1080 396.9625 435.0942 392.6341 462.2752 1100 374.8881 402.2369 536.4736 410.9039 1120 408.5592 409.7646 395.7876 460.3424 1140 397.1659 446.8943 430.1707 416.2954 1160 376.5157 412.6129 511.4492 423.5179 1180 391.9779 401.6266 451.6347 451.6958 1200 363.6983 436.4166 387.4461 420.5678

The data of Table 14 and FIG. 5 demonstrate that the w/o latices of Example 3 comprising 3 wt % of a carbonyl functional inversion agent invert faster than w/o latices comprising no inversion agent (control w/o latices) at room temperature in 3.5% SSW and as fast as w/o latices comprising 3 wt % glycerol at room temperature in 3.5% SSW. The data of Table 14 and FIG. 5 also demonstrate that the w/o latices of Example 3 comprising 3 wt % of a carbonyl functional inversion agent invert to a greater extent than w/o latices comprising no inversion agent (control w/o latices) at room temperature in 3.5% SSW and as completely as w/o latices comprising 3 wt % glycerol at room temperature in 3.5% SSW. The faster or comparable inversion rates and greater or comparable extent of inversion of the w/o latices comprising a carbonyl functional inversion agent provide better or comparable performance of the invertible latices than control w/o latices and w/o latices comprising glycerol under high stress conditions such as high TDS.

Example 8B

Torque data at 4° C. for w/o latices comprising 3 wt % of a carbonyl functional inversion agent are presented in Table 15 and FIG. 6.

TABLE 15 Torque data at 4° C. of w/o latices of Example 3 comprising 3 wt % of a carbonyl functional inversion agent. Torque (g · cm) Time (sec) Control Glycerol CMPG 1 CMPG 2 0 0.2441 0.0559 0.4272 −0.7579 20 17.2323 85.0983 56.5796 60.2773 40 112.0402 263.9313 262.2681 230.4637 60 150.6958 411.0260 313.8428 348.2615 80 193.5221 478.5716 418.6198 425.6744 100 225.3621 628.4129 509.1553 570.0226 120 215.0879 700.9430 534.3831 516.4134 140 305.3182 589.5538 570.2922 623.3266 160 306.8441 512.1409 513.8346 577.3468 180 334.3099 565.7501 667.5415 537.2670 200 287.2111 553.2379 657.3690 525.0600 220 293.3146 643.6717 536.9263 607.7627 240 317.7287 623.4283 586.2630 625.6663 260 303.3854 702.8758 577.2095 694.5343 280 336.9548 657.9132 689.4124 664.4236 300 341.1255 561.6811 645.9757 449.0712 320 357.5033 678.7669 602.6408 722.6105 340 376.1190 588.4349 650.6551 645.7062 360 352.4170 667.2719 632.4463 686.7015 380 361.4705 609.5937 668.0501 670.7306 400 381.4087 661.2701 621.4600 598.3022 420 384.9691 612.6455 601.0132 596.6746 440 395.7520 557.0017 531.6366 635.0250 460 376.0173 625.4628 501.9328 670.3237 480 376.4242 651.3011 570.9025 615.5955 500 426.9816 604.8126 656.9621 706.6396 520 414.4694 582.0262 607.9305 540.5223 540 378.0518 599.4212 563.6800 615.1886 560 394.7347 561.8846 521.8709 601.4557 580 396.8709 574.0916 489.5223 670.4254 600 396.6675 550.7965 637.9395 652.3183 620 417.0125 573.0743 513.4277 498.9166 640 394.9382 558.7311 638.1429 495.4580 660 393.3105 513.1582 512.8174 571.4467 680 389.3433 484.0647 507.7311 697.2809 700 403.3813 494.4407 465.0065 668.2892 720 398.6003 585.6883 503.7638 707.5551 740 397.0744 553.4414 616.4754 531.9773 760 393.6157 519.1600 529.0934 495.0511 780 403.0762 520.2789 479.9601 497.2890 800 413.5539 487.7268 509.0535 549.5758 820 402.5675 490.0665 525.5330 490.6769 840 393.1071 567.5812 621.4600 490.5752 860 380.1880 509.2926 527.0589 472.6715 880 401.7537 476.9440 467.5496 576.4313 900 395.0399 474.5026 597.8597 513.0564 920 412.6383 455.5817 530.3141 472.3663 940 386.8001 663.4064 517.9036 494.6442 960 403.0762 672.7651 528.6865 655.3701 980 403.1779 460.4645 554.3213 500.1373 1000 395.7520 468.3990 512.7157 468.8059 1020 404.2969 475.9267 525.2279 677.5462 1040 401.6520 492.4062 497.7620 591.6901 1060 396.1589 475.1129 470.6014 562.5966 1080 402.7710 481.7251 515.2588 485.5906 1100 390.7674 567.9881 586.2630 455.0730 1120 395.9554 488.5406 450.7650 644.8924 1140 400.5330 505.8339 464.2944 546.0154 1160 398.1934 477.8595 519.8364 491.9993 1180 392.5985 456.0903 459.1064 467.8904 1200 396.8709 623.5301 466.3289 587.9262

The data of Table 15 and FIG. 6 demonstrate that the w/o latices of Example 3 comprising 3 wt % of a carbonyl functional inversion agent invert faster than w/o latices comprising no inversion agent (control w/o latices) at 4° C. in 3.5% SSW and as fast as w/o latices comprising 3 wt % glycerol at 4° C. in 3.5% SSW. The data of Table 15 and FIG. 6 also demonstrate that the w/o latices of Example 3 comprising 3 wt % of a carbonyl functional inversion agent invert to a greater extent than w/o latices comprising no inversion agent (control w/o latices) at 4° C. in 3.5% SSW and as completely as w/o latices comprising 3 wt % glycerol at 4° C. in 3.5% SSW. The faster or comparable inversion rates and greater or comparable extent of inversion of the w/o latices comprising a carbonyl functional inversion agent provide better or comparable performance of the invertible latices than control w/o latices and w/o latices comprising glycerol under high stress conditions such as high TDS.

The results of Examples 7 and 8 demonstrate that w/o latices comprising a carbonyl functional inversion agent provide improved performance of the invertible latices over control w/o latices and w/o latices comprising glycerol under high stress conditions such as high TDS and across a broad range of temperatures.

Example 9

The surface tension of carbonyl functional inversion agents at 0.5 wt % was measured in a Kruss-K12 processor tensiometer at room temperature. The tested samples were prepared in deionized water and were neutralized with NaOH or H₂SO₄. Data is presented in Table 16 as an average +/− standard deviation (SD) of two experiments.

TABLE 16 Surface tension data of carbonyl functional inversion agents. Inversion Agent or Comparative Surface Tension (mN/m) SD None (deionized water) 72.13 0.14 Lauric Acid 22.17 0.15 CMPG1 64.77 0.11 CMPG2 63.45 0.24 CMG 67.55 0.21 Glycolic Acid 60.06 0.09 Lactic Acid 59.20 0.27 Malic Acid 60.73 0.26 Glycine 60.23 0.34 NHSI 57.62 0.24

The data of Table 16 demonstrate that carbonyl functional inversion agents do not reduce the surface tension of water or reduce the surface tension of water by 20% or less. By comparison, a known surfactant, lauric acid, reduces the surface tension of water by about 69%.

The invention illustratively disclosed herein can be suitably practiced in the absence of any element which is not specifically disclosed herein. Additionally each and every embodiment of the invention, as described herein, is intended to be used either alone or in combination with any other embodiment described herein as well as modifications, equivalents, and alternatives thereof. In various embodiments, the invention suitably comprises, consists essentially of, or consists of the elements described herein and claimed according to the claims. It will be recognized that various modifications and changes may be made without following the example embodiments and applications illustrated and described herein, and without departing from the scope of the claims. 

1. A water-in-oil latex comprising about 15 wt % to 70 wt % of a water soluble or dispersible polymer comprising 1 mol % to about 100 mol % acrylamide monomers; about 0.1 wt % to 20.0 wt % of an inversion surfactant characterized as having a hydrophilic/lipophilic balance of 10 or greater; and about 0.1 wt % to 20.0 wt % of an inversion agent that is a carbonyl functional inversion agent.
 2. The latex of claim 1 comprising about 1.0 wt % to 20.0 wt % of the inversion agent and inversion surfactant combined.
 3. The latex of claim 1, wherein the inversion agent is selected from hydroxycarboxylic acids or salts thereof, hydroxyamides, hydroxamates, and amino acids.
 4. The latex of claim 3, wherein the hydroxycarboxylic acid or salt thereof is a carboxymethyl polyol ether.
 5. The latex of claim 4, wherein the carboxymethyl polyol ether is a carboxymethyl-1,2-diol, carboxymethyl erythritol, carboxymethyl sorbitol, carboxymethyl polyglycerol, or carboxymethyl glycerol.
 6. The latex of claim 3, wherein the hydroxycarboxylic acid is an α-hydroxyacid or a β-hydroxyacid.
 7. The latex of claim 6, wherein the α-hydroxyacid is glycolic acid, lactic acid, tartaric acid, or malic acid and the β-hydroxyacid is hydroxypropionic acid, carnitine, or salicylic acid.
 8. The latex of claim 1 comprising about 0.1 wt % to 5.0 wt % of the inversion agent.
 9. The latex of claim 1 comprising about 3 wt % to 50 wt % water; about 10 wt % to 40 wt % of a compound or blend thereof that is less than 0.1 wt % soluble in water at 25° C. and is substantially a liquid over the range of 20° C. to 90° C. and comprising linear, branched, or cyclic hydrocarbon moieties; about 20 wt % or less of a latex surfactant characterized as having a hydrophilic/lipophilic balance of between 2 and 10; and about 0.1 wt % to 5.0 wt % of the inversion agent, wherein the inversion agent is not a surfactant.
 10. The latex of claim 1, wherein the inversion agent is a hydrotrope.
 11. The latex of claim 1, wherein the inversion agent is characterized as having a hydrophilic/lipophilic balance of greater than about
 19. 12. The latex of claim 1, wherein the latex is shelf stable.
 13. The latex of claim 1, wherein the latex has a bulk viscosity at least 15% lower than the same latex excluding the inversion agent.
 14. A method of forming an invertible latex, the method comprising (a) forming a water-in-oil latex comprising about 15 wt % to 70 wt % of a water soluble or dispersible polymer; about 3 wt % to 50 wt % water; about 10 wt % to 40 wt % of a compound or blend thereof that is less than 0.1 wt % soluble in water at 25° C. and is substantially a liquid over the range of 20° C. to 90° C. and comprising linear, branched, or cyclic hydrocarbon moieties; and about 20 wt % or less of a latex surfactant characterized as having a hydrophilic/lipophilic balance of between 2 and 10; and (b) adding to the latex about 0.1 wt % to 20.0 wt % of an inversion surfactant characterized as having a hydrophilic/lipophilic balance of 10 or greater and about 0.1 wt % to 5.0 wt % of a carbonyl functional inversion agent to form an invertible latex.
 15. The method of claim 14, wherein the invertible latex is shelf stable.
 16. The method of claim 14, wherein the inversion agent is selected from hydroxycarboxylic acids or salts thereof, hydroxyamides, hydroxamates, and amino acids.
 17. The method of claim 16, wherein the hydroxycarboxylic acid or salt thereof is a carboxymethyl polyol ether selected from carboxymethyl-1,2-diol, carboxymethyl erythritol, carboxymethyl sorbitol, carboxymethyl polyglycerol or carboxymethyl glycerol.
 18. The method of claim 16, wherein the hydroxycarboxylic acid is an α-hydroxyacid selected from glycolic acid, lactic acid, tartaric acid, and malic acid, or a β-hydroxyacid selected from hydroxypropionic acid, carnitine, and salicylic acid.
 19. A method of recovering hydrocarbon compounds from a subterranean reservoir, the method comprising (a) forming an invertible latex according to the method of claim 12, (b) adding a water source to the invertible latex in a single addition to form a polymer flooding solution comprising about 100 ppm to 10,000 ppm of the water soluble or dispersible polymer, (c) injecting the polymer flooding solution into the subterranean reservoir, and (d) recovering the hydrocarbon compounds.
 20. The method of claim 19, wherein the water source is about 30° C. to 100° C.
 21. The method of claim 19, wherein the water source includes about 0.1 to 30 wt % total dissolved solids.
 22. The method of claim 19, wherein the water source is about 30° C. to 100° C. and includes about 0.1 to 30 wt % total dissolved solids. 